CN114695723A - Optoelectronic device - Google Patents

Abstract

The application belongs to the technical field of show, especially, relate to a photoelectric device, including positive pole, hole transport layer, quantum dot luminescent layer and the negative pole that stacks gradually the setting, contain the quantum dot material of nucleocapsid structure in the quantum dot luminescent layer, the crust layer of quantum dot material is ZnSeS, hole transport material's mobility is higher than 1x10 in the hole transport layer^‑4cm²Vs. According to the photoelectric device provided by the application, the outer shell layer of the quantum dot adopts ZnSeS, the constraint capacity of excitons in the quantum dot core-shell structure is moderate, the influence of the outer shell layer on the tunneling effect of current carriers is small, and the valence delta E is constructed_EML‑HTLThe hole injection barrier is more than or equal to 0.5eV, and the valence band top energy level of the required hole transport material is relatively shallow. The hole mobility of the HTL material is 1x10 or more^‑4cm²And when the material is/Vs, the requirements of constructing a hole injection barrier and ensuring the efficiency of hole transmission injection into the quantum dot material can be met simultaneously.

Description

Optoelectronic device

Technical Field

The application belongs to the technical field of display, and particularly relates to a photoelectric device.

Background

Quantum dot light emitting display technology (QLED) is a new display technology that has been rapidly developed in recent years, and QLED is an active light emitting technology similar to Organic Light Emitting Display (OLED), and thus has the advantages of high light emitting efficiency, fast response speed, high contrast, wide viewing angle, and the like. Due to the excellent material characteristics of quantum dots in the QLED display technology, the QLED has more performance advantages than the OLED in many aspects, such as: the luminescence of the quantum dots is continuously adjustable, the luminescence width is extremely narrow, and wider color gamut and higher purity display can be realized; the QLED has better device stability due to the inorganic material characteristics of the quantum dots; the driving voltage of the QLED device is lower than that of the OLED, so that higher brightness can be realized, and the energy consumption can be further reduced; meanwhile, the QLED display technology is matched with the production process and technology of printing display, and the high-efficiency mass production preparation with large size, low cost and capability of curling can be realized. Therefore, QLED is considered as one of the first technologies for future next generation display screens with light weight, portability, flexibility, transparency, and high performance.

Because of the similarity of the QLED and the OLED display technology in the light emitting principle, in the development process of the QLED display technology, the device structure of the QLED is more based on the OLED display technology, except that the light emitting layer material is replaced by the organic light emitting material, and other functional layer materials such as a charge injection layer or a charge transport layer are often made of materials existing in the OLED. Meanwhile, the explanation of device physics in the QLED device, the selection of the energy level of the functional layer material, the collocation principle and the like all follow the existing theoretical system in the OLED. The classical device physical conclusion obtained in OLED device research is applied to a QLED device system, and the QLED device performance is improved remarkably, especially the QLED device efficiency.

However, the classical thought and strategy formed in the OLED at present cannot effectively improve the life of the QLED device, and although the efficiency of the QLED device can be improved through the classical thought and strategy of the OLED device, research finds that the device life of the high-efficiency QLED device is significantly inferior to that of a similar device with lower efficiency. Therefore, the existing QLED device structure designed based on the OLED device theoretical system cannot simultaneously improve the photoelectric efficiency and the service life performance of the QLED device. Corresponding to the unique device mechanism of the QLED device system, a new and more targeted QLED device structure needs to be developed.

Disclosure of Invention

An object of the application is to provide a photoelectric device, aim at solving to a certain extent prior art and be difficult to the photoelectric efficiency and the life-span performance's of improving QLED device simultaneously problem.

In order to achieve the purpose of the application, the technical scheme adopted by the application is as follows:

the present application provides a photovoltaic device comprising: the quantum dot light-emitting diode comprises an anode, a hole transport layer on the anode, a quantum dot light-emitting layer on the hole transport layer and a cathode on the quantum dot light-emitting layer, wherein the quantum dot light-emitting layer comprises a quantum dot material with a core-shell structure, the outer shell layer of the quantum dot material is ZnSeS, and the mobility of the hole transport material in the hole transport layer is higher than 1x10^-4cm²/Vs。

According to the photoelectric device provided by the first aspect of the application, the outer shell layer of the quantum dot adopts ZnSeS, the band gap width of the ZnSeS is between ZnSe and ZnS, the constraint capacity of excitons in the quantum dot core-shell structure is moderate, and the influence of the outer shell layer on the tunneling effect of a current carrier is small. Meanwhile, the valence band energy level of the ZnSeS shell material is between ZnSe and ZnS, and the valence band top energy level difference (Delta E) needs to be constructed_EML-HTL) A hole injection barrier of 0.5eV or more requires a hole transport material having a relatively shallow top valence band energy. Therefore, the hole mobility of the HTL material is 1 × 10 or more^-4cm²And when the material is/Vs, the requirements of constructing a hole injection barrier and ensuring the efficiency of hole transmission injection into the quantum dot material can be met simultaneously.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic view of the structure of an optoelectronic device provided in the first aspect of the present application;

FIG. 2 is a schematic diagram of a photovoltaic device provided in a second aspect of the present application;

fig. 3 is a schematic view of a photovoltaic device provided in a third aspect of the present application;

fig. 4 is a schematic view of a photovoltaic device provided in a fourth aspect of the present application;

fig. 5 is a schematic view of a photovoltaic device provided in a fifth aspect of the present application;

fig. 6 is a schematic structural view of a photovoltaic device provided in a sixth aspect of the present application;

FIG. 7 is a schematic representation of the structure of an optoelectronic device provided in a seventh aspect of the present application;

fig. 8 is a schematic structural view of a photoelectric device provided in an eighth aspect of the present application;

FIG. 9 is a schematic view of a photovoltaic device provided in a ninth aspect of the present application;

fig. 10 is a schematic view of a structure of a photovoltaic device provided in a tenth aspect of the present application;

fig. 11 is a schematic view of a photovoltaic device provided in an eleventh aspect of the present application;

fig. 12 is a schematic view of a photovoltaic device provided in a twelfth aspect of the present application;

fig. 13 is a schematic view of a photovoltaic device provided in a thirteenth aspect of the present application;

fig. 14 is a schematic positive structure diagram of a quantum dot light emitting diode provided in an embodiment of the present application;

fig. 15 is a schematic view of an inversion structure of a quantum dot light emitting diode provided in an embodiment of the present application;

fig. 16 is a test chart of the light emitting life of the quantum dot light emitting diode provided in embodiments 1 to 7 of the present application;

fig. 17 is a test chart of the light emitting life of the quantum dot light emitting diode provided in embodiments 8 to 9 of the present application;

FIG. 18 is a test chart of the light emitting life of the quantum dot light emitting diode provided in embodiments 10 to 11 of the present application;

FIG. 19 is a graph showing the relationship between the voltage and the time of the quantum dot light emitting diode provided in embodiments 12 to 14 of the present application;

FIG. 20 is a graph showing the relationship between the voltage and the time of the quantum dot light emitting diode provided in embodiments 15 to 19 of the present application;

fig. 21 is a test chart of the light emitting life of the quantum dot light emitting diode provided in embodiments 20 to 25 of the present application;

FIG. 22 is a graph illustrating the lifetime of quantum dot light-emitting diodes provided in embodiments 26 to 28 of the present application;

FIG. 23 is a test chart of the light emitting life of the QDs provided in embodiments 29 to 31 of the present application;

fig. 24 is a test chart of the light emitting life of the qd-led provided in embodiments 32 to 35 of the present application;

FIG. 25 is a test chart of the light emitting life of the quantum dot light emitting diode provided in embodiments 36 to 38 of the present application;

FIG. 26 is a graph showing the relationship between the voltage and the time of the quantum dot light emitting diode provided in embodiments 39 to 41 of the present application;

FIG. 27 is a graph showing the measured lifetime of quantum dot light-emitting diodes according to embodiments 39 to 41 of the present application;

FIG. 28 is a graph showing the relationship between the voltage and the time of the QDs provided in embodiments 42 to 43 of the present application;

fig. 29 is a test chart of the light emitting life of the qd-led provided in embodiments 42 to 43 of the present application.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application more clearly apparent, the present application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

In this application, the term "and/or" describes an association relationship of associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a is present alone, A and B are present simultaneously, and B is present alone. Wherein A and B can be singular or plural.

In the present application, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (one) of a, b, or c," or "at least one (one) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, and c may be single or plural, respectively.

It should be understood that, in various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, some or all of the steps may be executed in parallel or executed sequentially, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application. The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the examples of this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

In the examples of the present application, Δ E_HTL-HIL＝E_HOMO,HTL-E_HIL，ΔE_EML-HTL＝E_HOMO,EML-E_HTLAll energy level/work function values are absolute values, wherein a large energy level absolute value indicates a deep energy level, and a small energy level absolute value indicates a shallow energy level.

The key of the application is to improve the service life and the photoelectric efficiency of the QLED device at the same time. At present, there is a significant difference between the testing of device lifetime and the characterization of device efficiency: the time for testing the efficiency of the device is usually short, so that the QLED device is characterized by the instantaneous state at the starting time of working; device lifetime, in turn, characterizes the ability of the device to maintain device efficiency after it has been continuously operated and has entered a steady state.

At present, based on the existing theoretical systems of conventional OLED devices, it is believed that electrons are generally injected into the light-emitting layer at a faster rate than holes. Therefore, in order to balance and improve the recombination efficiency of holes and electrons in the light emitting layer of the QLED device, a hole injection layer is usually disposed in the device, and the injection barrier between two adjacent functional layers is reduced as much as possible to enhance the hole injection efficiency, thereby improving the carrier injection efficiency and reducing the interface charge accumulation. However, the method can only improve the photoelectric efficiency of the QLED device at the starting moment to a certain extent, but cannot simultaneously improve the lifetime of the device, or even reduce the lifetime of the device. Through the gradual development and deepening of the research on the mechanism of the QLED device, the QLED device system is found to have some special mechanisms different from the OLED device system due to the use of quantum dot materials and other nano materials with special material surfaces, and the mechanisms are closely related to the performance of the QLED device, particularly the service life of the device.

Specifically, the application finds out through research that: when the QLED device is in an initial working state, the electron injection rate in the luminescent layer is faster than that of holes, so that the quantum dot material is negatively charged, and the negative charge state can be maintained due to the structural characteristics of the quantum dot material, the constraint effect of a surface ligand, the Coulomb blocking effect and other factors. However, the negative charge state of the quantum dot material makes further injection of electrons more and more difficult during continuous operation of the QLED device, thereby resulting in an imbalance between actual injection of electrons and holes in the light emitting layer. Further, in the process of the continuous lighting operation of the QLED device to the stable state, the negative charge state of the quantum dot material also tends to be stable, that is, the electrons newly captured and bound by the quantum dots and the electrons consumed by the radiation transition reach a dynamic balance. In this case, the injection rate of electrons into the light-emitting layer is much lower than that in the initial state, and the hole injection rate required for achieving charge injection balance in the light-emitting layer is actually relatively low. If the injection efficiency of the hole is improved based on the theoretical system of the traditional OLED device, the instant balance of charge injection can be formed only at the initial working stage of the QLED device by adopting the hole transport layer with the deep energy level, and the high device efficiency at the initial stage is achieved. However, as the QLED device enters a stable operating state, excessive hole injection may adversely increase the imbalance between electrons and holes in the light-emitting layer of the device, and the efficiency of the QLED device may not be maintained and may decrease accordingly. And this charge imbalance condition is exacerbated as the device continues to operate, resulting in a correspondingly rapid decay in QLED device life.

Therefore, in order to realize the injection balance of carriers in the light emitting layer of the device and obtain a device with higher efficiency and longer service life, the key to finely regulate and control the injection of carriers of holes and electrons at two sides of the device is as follows: on one hand, the injection rate of holes is regulated to a lower rate, so that the injection rate of holes and the injection rate of electrons in the stable working state of the QLED device are balanced, and the recombination efficiency of the QLED device is improved. On the other hand, since the hole injection rate required for the QLED device in a practically stable operation state is lower than conventionally expected, carrier accumulation easily occurs, causing irreversible damage to the device. Therefore, the influence of carrier accumulation on the device lifetime is avoided as much as possible, and the device lifetime is improved.

As shown in fig. 1, a first aspect of the embodiments of the present application provides an optoelectronic device, including: the quantum dot light-emitting layer comprises a quantum dot material with a core-shell structure, and the valence band top energy level difference between the shell material of the quantum dot material and the cavity transport material in the cavity transport layer is more than or equal to 0.5 eV.

The photoelectric device provided by the first aspect of the application constructs a valence band top energy level difference (E) of more than or equal to 0.5eV between the shell layer material of the quantum dot material and the hole transport material_EML-HTLNot less than 0.5 eV. The injection efficiency of holes is reduced by increasing the hole injection barrier, thereby balancing the injection balance of holes and electrons in the light-emitting layer. Based on the energy level characteristics of the current hole transport material and the energy level characteristics of the shell material of the quantum dot material, the application finds that at least delta E is required through research_EML-HTLThe energy level barrier of more than or equal to 0.5eV can realize the obvious reduction of the hole injection efficiency, and the electron injection efficiency and the hole injection efficiency in the luminescent layer are balanced. In addition, the present application Δ E_EML-HTLThe hole injection barrier of more than or equal to 0.5eV does not cause that holes cannot be injected, because the energy level of the outer shell layer of the quantum dot can generate energy band bending in the electrified working state, and a carrier can realize injection through a tunneling effect; thus, the increase of the energy level barrier does not completely hinder the final injection of carriers, although it causes the reduction of the carrier injection rate.

Quantum dot materials are generally semiconducting from groups II-IV, II-VI, II-V, III-VI, IV-VI, I-III-VI, II-IV-V, etc. of the periodic Table of the elementsA core-shell structure composed of the compound or at least two of the semiconductor compounds. In some embodiments, the quantum dot material of the core-shell structure comprises an inner core and an outer shell. In other embodiments, the quantum dot material with the core-shell structure comprises a core, a shell, and an intermediate bridge layer between the core and the shell, wherein the intermediate bridge layer may be one layer or multiple layers. The core material in the quantum dot material with the core-shell structure determines the luminescence property, the shell material protects the luminescence stability of the core, the injection of current carriers is facilitated, and electrons and holes are injected into the core through the shell layer to emit light. The band gap of the core is narrower than that of the shell, so the valence band energy level difference between the hole transport material and the quantum dot core is smaller than that between the hole transport material and the quantum dot shell. Thus, example Δ E of the present application_EML-HTL0.5eV or more can ensure effective injection of hole carriers into the core of the quantum dot material. The specific structure and the specific material type of the quantum dot material with the core-shell structure are further described in the embodiments below according to different application situations.

In some embodiments, the difference between the valence band top energy level of the shell material of the quantum dot material and the valence band top energy level of the hole transport material in the hole transport layer is 0.5-1.7 eV, i.e., Δ E_EML-HTLThe energy level barrier in the range is 0.5eV to 1.7eV, and the energy level barrier is constructed between the shell layer material of the quantum dot material and the hole transport material, so that the quantum dot material can be suitable for device systems constructed by different hole transport materials and quantum dot materials, and the injection balance of electrons and holes in different device systems is optimized. In practical application, different energy level differences Delta E of the top valence band can be set according to specific material properties_EML-HTLIn the case of (1), the carrier injection rate of holes and electrons on both sides of the light-emitting layer is finely controlled to balance the hole and electron injection.

In some embodiments, the valence band top energy level difference between the shell material of the quantum dot material and the hole transport material is 0.5eV to 0.7eV, in this case, TFB, P12, and P15 can be adopted as the hole transport material, and ZnSe and CdS are adopted as the shell material of the quantum dot, for example: TFB-ZnSe, P12/P15-CdS and other device systems.

In some embodiments, the valence band top energy level difference between the shell material of the quantum dot material and the hole transport material is 0.7eV to 1.0eV, in this case, TFB and P09 can be adopted as the hole transport material, and ZnSe and CdS as the quantum dot shell material, for example: P09-ZnSe, TFB-CdS and other device systems.

In some embodiments, the valence band top energy level difference between the shell material of the quantum dot material and the hole transport material is 1.0eV to 1.4eV, in this case, TFB, P09, P13, and P14 can be used as the hole transport material, and the shell material of the quantum dot is CdS, ZnSe, and ZnS, for example: TFB-ZnS, P09-CdS, P13/P14-ZnSe and other device systems.

In some embodiments, the valence band top energy level difference between the shell layer material of the quantum dot material and the hole transport material is greater than 1.4eV to 1.7eV, and P09-ZnS, P13/P14-ZnS and other device systems can be adopted.

In one aspect, since the hole injection layer in the current device is often used to improve the hole injection efficiency, the QLED device in the embodiments of the present application needs to regulate the hole injection to a lower rate in a certain manner. Accordingly, in some embodiments, the optoelectronic device provided by the first aspect of embodiments of the present application may not have a hole injection layer.

On the other hand, the arrangement of the hole injection layer in the QLED device not only can improve the hole injection efficiency, but also can adjust the hole smooth and balanced injection, which is one of the key performance factors affecting the performance, the lifetime, and the like of the device. Therefore, the hole injection efficiency in the device can be further regulated and controlled by arranging the hole injection layer in the device, and the influence of charge accumulation on the service life of the device is reduced. Specifically, the method comprises the following steps:

in general, in the research on the performance of the QLED device, more attention is paid to the interface damage caused by the charge accumulation on both sides of the EML of the emission layer, such as the HTL or ETL interface, and the quenching of the exciton in the EML emission layer. In practice, charge accumulation is also easily formed on the interface energy level barrier from the HIL to the HTL, so that the interface between the HIL and the HTL is irreversibly damaged by an electric field, which causes the voltage of the device to increase and the brightness of the device to decrease. Moreover, the voltage rise of the QLED device caused at this time is significantly different from the voltage rise caused by charge accumulation at the EML interface as follows: the disruption of the interface between the HIL and HTL, which typically is irreversible due to the electric field created by charge accumulation, can occur as the device continues to be powered on, i.e., continues to deteriorate; whereas the charge accumulation at the EML interface is reversible and will reach a certain degree of saturation. Therefore, the interface charge accumulation between the HIL and the HTL has a greater influence on the performance of the device, such as the lifetime.

On one hand, in order to reduce irreversible damage to the service life performance of the device caused by HIL and HTL interface charge accumulation, the embodiment of the application optimizes the injection and recombination efficiency of carriers in the QLED device. In a second aspect of the embodiments of the present application, there is provided, in addition to or as a sole result of the embodiments of the first aspect, an optoelectronic device comprising a first hole injection layer, the first hole injection layer being located between the anode layer and the hole transport layer, and an absolute value of a difference between a top valence band level of the material of the hole transport layer and a work function of the first hole injection material in the first hole injection layer being 0.2eV or less.

The optoelectronic device provided by the second aspect of the present application, by defining | Δ E_HTL-HILThe | is less than or equal to 0.2eV, so that a hole injection energy level barrier between the HTL and the HIL can be obviously reduced, the injection efficiency of holes from the anode is improved, the effective injection of the holes from the HIL to the HTL is facilitated, the barrier and interface charges are eliminated, the overall resistance of the device is reduced, the irreversible damage caused by charge accumulation at the interface between the HIL and the HTL is reduced, the driving voltage of the device is reduced, and the service life of the device is prolonged. If Δ E_HTL-HILIf | is greater than 0.2eV, charge accumulation is easily formed on the interface energy level barrier from the HIL to the HTL, so that the interface between the HIL and the HTL is irreversibly damaged under the action of an electric field, and thus, the voltage of the device is increased, and the brightness of the device is attenuated.

In some embodiments, the absolute value of the difference between the top valence band energy level of the hole transport layer material and the work function of the first hole injection material is 0 eV. | Δ E of the embodiment of the present application_HTL-HILThe | is 0, the effective injection effect of the holes from the HIL to the HTL is good, the potential barrier and the interface charges are eliminated, the overall resistance of the device is reduced, and therefore the driving electricity of the device is reducedAnd the service life of the device is prolonged.

In some embodiments, the first hole injection material has a work function of 5.3eV to 5.6eV in absolute value, which is relatively close to the absolute value of the valence band energy level of current conventional hole transport materials (around 5.4eV), which is beneficial for controlling | Δ E_HTL-HILAnd the I is in a lower range, so that the energy levels of the two are basically flush, potential barriers and interface charges are eliminated, the driving voltage of the device is reduced, and the service life of the device is prolonged. Embodiments of the present application enable |. DELTA.E by selecting HIL and HTL materials with appropriate energy levels_HTL-HIL| 0.2eV or less, the energy level barrier from the HIL to the HTL and the charge accumulation at the interface can be effectively eliminated, thereby reducing irreversible damage caused at the interface between the HIL and the HTL.

In some embodiments, the hole transport material has a mobility greater than 1 × 10^-4cm²Vs. The mobility adopted by the embodiment of the application is higher than 1x10^-4cm²The inventor finds that the hole transport material with the mobility can improve the hole transport migration effect, prevent charge accumulation, eliminate interface charges, better reduce the driving voltage of the device and prolong the service life of the device through a large number of experiments.

On the other hand, in order to reduce the hole injection rate in the QLED device, regulate and control the injection and recombination efficiency of carriers, and reduce irreversible damage to the service life performance of the device caused by charge accumulation at the interface of the HIL and the HTL. In a third aspect of the embodiments of the present application, there is provided, in addition to or as a separate item from the embodiment of the first aspect, an optoelectronic device including a second hole injection layer, the second hole injection layer being located between the anode layer and the hole transport layer, and a difference between a top valence band energy level of a material of the hole transport layer in the hole transport layer and a work function of a second hole injection material in the second hole injection layer being less than-0.2 eV, as shown in fig. 3.

The optoelectronic device provided in the third aspect of the present application is manufactured by constructing an injection barrier, i.e., Δ E, of less than-0.2 eV between the hole transport layer material and the second hole injection material_HTL-HILLess than-0.2 eV, and the hole injection barrier from the anode to the HIL is increased, so that the hole injection in the QLED device is reducedThe overall rate effectively controls the number of holes entering the QLED device. On one hand, the speed of injecting holes into the luminescent layer is effectively reduced, the hole electron injection speed in the luminescent layer is balanced, and the carrier recombination efficiency is improved; on the other hand, the charge accumulation formed at the interface of the HTL and the HIL due to excessive hole injection can be avoided, and the irreversible damage effect of the interface charge accumulation on the service life of the device can be prevented. Meanwhile, a hole blocking barrier from the HTL to the HIL is formed, so that holes are prevented from being diffused to the HIL layer, the utilization rate of the holes is improved, and the holes are ensured to effectively survive before being injected into the light emitting layer. On the basis of ensuring that the current carriers are injected into the device in a balanced working state, holes injected into the device are fully and effectively utilized, the luminous efficiency of the device is further ensured, and the efficiency and the service life of the device are improved at the same time.

In some embodiments, the quantum dot material of core-shell structure included in the quantum dot light emitting layer of the optoelectronic device has a valence band top energy level difference of greater than 0eV, i.e., Δ Ε, between the outer shell material and the hole transport material_EML-HTLThe energy level of the light-emitting layer is deeper than that of the hole transport layer when the energy level is more than 0; meanwhile, an injection barrier (delta E) smaller than-0.2 eV exists between the hole transport layer material and the second hole injection material_HTL-HIL< -0.2eV, and the energy level of the hole injection layer is deeper than that of the hole transport layer. At this time, a deep-shallow-deep energy level structure is formed between the light emitting layer, the hole transport layer and the hole injection layer, so that holes injected into the hole transport layer form a hole carrier trap, and accumulated holes are effectively stored and are not diffused to other functional layers or interfaces except the HTL layer. And further eliminating the influence of interface charges on the device, and on the basis of ensuring the injection balance of current carriers in the stable working state of the device, more fully and effectively utilizing holes injected in the device, further ensuring the luminous efficiency of the device, and realizing the improvement of the efficiency and the service life of the device. In some embodiments, the difference in valence band top energy levels of the shell layer material of the quantum dot material and the hole transport material is greater than or equal to 0.5 eV; in other embodiments, the difference between the valence band top energy levels of the shell layer material and the hole transport material of the quantum dot material can be 0.5eV to 1.7eV, i.e., Δ E_EML-HTL0.5eV to 1.7eV, in factExperiments prove that the hole carrier trap formed by the embodiment has a good effect, and injection balance of holes and electrons in a light-emitting layer of the device is more finely regulated and controlled in the practical application process through the hole carrier trap, so that carrier recombination efficiency is improved.

In some embodiments, the difference between the top valence band energy level of the hole transport layer material and the work function of the second hole injection material is in the range of-0.9 eV to-0.2 eV, Δ E_HTL-HILThe difference is-0.9 eV to-0.2 eV, and the hole injection and transmission within the range have good balance effect. If the thickness is less than-0.9 eV, the hole injection resistance is increased, so that the hole injection amount is reduced, and the balanced injection and effective recombination of holes and electrons in the light-emitting layer are influenced; if the potential barrier is larger than-0.2 eV, holes are easily accumulated at the interface, and the utilization rate is not high.

In some embodiments, the second hole injection material has a work function absolute value in the range of 5.4eV to 5.8 eV. The second hole injection material in the embodiment of the application has a work function absolute value of 5.4 eV-5.8 eV, and a hole blocking barrier with an energy difference smaller than-0.2 eV is formed between the second hole injection material and the hole transport material in the range. Specifically, the valence band absolute value of the conventional hole transport material is about 5.3-5.4eV, and the second hole injection material with the work function absolute value of more than or equal to 5.4eV can form a negative energy level difference of less than-0.2 eV with the conventional hole transport material, so that a hole blocking barrier is formed, the hole injection rate is optimized, and the hole utilization rate is improved.

In some embodiments, the hole transport material has a mobility greater than 1 × 10^-4cm²Pervs, the examples of the present application use mobilities higher than 1 × 10^-4cm²The hole transport material of/Vs further ensures the transport and migration effect of holes, prevents charge accumulation, eliminates interface charges, better reduces the driving voltage of the device and prolongs the service life of the device.

In the embodiments of the second and third aspects of the present application described above, the hole injection material is preferably a metal oxide material. That is, in some embodiments, when the optoelectronic device comprises a first hole injection layer, the first hole injection material in the first hole injection layer is selected from metal oxide materials. In other embodiments, when the optoelectronic device comprises a second hole injection layer, the second hole injection material in the second hole injection layer is selected from metal oxide materials. In the embodiments of the present application, the metal oxide material used for the hole injection material has better stability and no acidity, and not only can meet the requirements of the embodiments on hole injection, but also does not have negative effects on adjacent functional layers. The attenuation of the organic hole injection material to the service life of the device due to the damage of the thermal effect or the electrical effect in the working process of the device is avoided, and the damage of the acidity of the organic hole injection material to the adjacent functional layer is also avoided.

In some embodiments, the metal oxide material comprises: the metal nano material is at least one of tungsten oxide, molybdenum oxide, vanadium oxide, nickel oxide and copper oxide, has good stability and no acidity, and can construct energy level barriers with different sizes with a hole transport layer by regulating and controlling the work function in the practical application process, so that the regulation and control of hole injection and transmission are facilitated, the carrier recombination efficiency is improved, and the influence of charge accumulation on the service life of a device is reduced.

In some embodiments, the metal oxide material has a particle size of 2-10 nm, and the metal oxide material with a small particle size is beneficial to deposition to obtain a thin film with a compact film layer and a uniform thickness, so that the bonding tightness between the thin film and an adjacent functional layer is improved, the interface resistance is reduced, and the device performance is beneficial to improvement.

In other embodiments, organic hole injection materials such as poly (3, 4-ethylenedioxythiophene) -polystyrenesulfonic acid (PEDOT: PSS), HIL2, HIL1-1, HIL1-2, copper phthalocyanine (CuPc), 2,3,5, 6-tetrafluoro-7, 7',8,8' -tetracyanoquinone-dimethane (F4-TCNQ), 2,3,6,7,10, 11-hexacyano-1, 4,5,8,9, 12-Hexaazatriphenylene (HATCN), and the like can be used as the hole injection material. PSS comprises the following structural formula:

the work function of the organic molecule of (1) is-5.1 eV; HIL2 comprises the structural formula:

is provided withAn organic molecule having a work function of-5.6 eV; HIL1-1 and HIL1-2 both comprise the structural formula:

the work function of the HIL1-1 is-5.4 eV, and the work function of the HIL1-2 is-5.3 eV.

In some embodiments, the first hole injection layer has a thickness of 10 to 150 nm. In other embodiments, the second hole injection layer has a thickness of 10 to 150 nm. The thickness of the hole injection layer can be flexibly regulated and controlled according to the actual application requirements, and meanwhile, the hole injection rate can be well adjusted through adjusting the thickness of the hole injection layer.

Further, in the examples of the present application, to construct Δ E_EML-HTLThe energy level potential barrier of more than or equal to 0.5eV realizes the purposes of reducing the hole injection rate in the QLED device and regulating the injection and recombination efficiency of carriers, and simultaneously reduces the irreversible damage of the charge accumulation of the HIL and HTL interface to the service life performance of the device. As shown in fig. 4, a fourth aspect of the embodiments of the present application provides an optoelectronic device, where a hole transport layer of the optoelectronic device includes at least two hole transport materials, and an absolute value of a top valence band energy level of at least one of the hole transport materials is 5.3eV or less. In a specific embodiment, the at least two hole transport materials include at least one hole transport material having a top valence band energy level of 5.3eV or less in absolute value and one hole transport material having a top valence band energy level of more than 5.3eV in absolute value.

The hole transport layer of the optoelectronic device provided by the fourth aspect of the present application is a mixed material layer containing a plurality of hole transport materials with different valence band top energy levels, wherein at least one hole transport material has a valence band top energy level of 5.3eV or less, and the shell energy level of the conventional quantum dot luminescent material is often relatively deep (6.0eV or more), so that an energy level difference of 0.5eV or more is formed between the hole transport material with a shallow energy level and the quantum dot shell material. In addition, hole transport with a top valence band energy level greater than 5.3eV is includedThe material can regulate and control the energy level difference between the hole transport material and the luminescent material shell layer in a small range and more finely. Therefore, the hole transport layer realizes the fine regulation and control of the hole injection barrier between the hole transport material and the quantum dot shell layer through the mutual collocation of the shallow level hole transport material with the absolute value less than or equal to 5.3eV and the deep level hole transport material with the absolute value greater than 5.3eV, and the hole mobility in the HTL layer can be regulated through the hole transport materials with different energy level depths. Realization of Delta E_EML-HTLThe energy level barrier of more than or equal to 0.5eV reduces the injection efficiency of holes by improving the hole injection barrier, thereby improving the injection balance of the holes and electrons in the luminescent layer, improving the luminous efficiency of the device and simultaneously reducing the influence of charge accumulation on the service life of the device.

In some embodiments, a hole transport layer of an optoelectronic device comprises at least two hole transport materials, wherein one hole transport material has a top valence band energy level of 5.3eV or less in absolute value and further comprises a hole transport material having a top valence band energy level of greater than 5.3eV and less than 5.8eV in absolute value. In some embodiments, the hole transport layer comprises at least two hole transport materials, one hole transport material having a top valence band energy level of 5.3eV or less in absolute value, and a hole transport material having a top valence band energy level of 5.8eV or more in absolute value. In other embodiments, the hole transport layer comprises at least three hole transport materials, one hole transport material having a top valence band energy level of 5.3eV or less in absolute value, a hole transport material having a top valence band energy level of greater than 5.3eV and less than 5.8eV in absolute value, and a hole transport material having a top valence band energy level of greater than 5.8eV in absolute value. According to the embodiment of the application, the shallow energy level material and the deep energy level material are mixed and matched, the hole injection barrier can be flexibly regulated and controlled according to factors such as practical application requirements and device systems, the injection energy level barrier from the hole to the luminescent material is larger than or equal to 0.5eV, the hole injection efficiency is reduced, the injection balance of the hole and the electron in the luminescent layer is balanced, and the application is flexible and convenient.

In some embodiments, when the hole transport layer includes a hole transport material having a top valence band energy level greater than 5.3eV and less than 5.8eV, at least one of an organic electron transport material layer, a metal oxide nanoparticle layer such as ZnO nanoparticles, and a sputter-deposited metal oxide layer may be used in the electron transport layer of the optoelectronic device. According to the embodiment of the application, when the hole transport layer comprises at least one hole transport material with the valence band top energy level less than or equal to 5.3eV and the valence band top energy level more than 5.3eV and less than 5.8eV, the hole transport layer has moderate valence band top energy level and hole mobility, so that the hole transport layer can be well matched with conventional metal oxides such as ZnO or organic electron transport materials, and the regulation and control of hole and electron charge balance are facilitated.

In some embodiments, when the hole transport layer includes a hole transport material having a valence band top energy level of 5.8eV or more, metal oxide nanoparticles, preferably with fewer surface groups attached, may be employed in the electron transport layer of the optoelectronic device. According to the embodiment of the application, when the hole transport layer comprises the hole transport material with the valence band top energy level larger than 5.8eV, the difference between the energy level and the mobility of the hole transport layer and the hole transport layer material with the shallow valence band top energy level with the valence band top energy level smaller than or equal to 5.3eV of the hole transport material is large, continuous regulation and control in a large window range can be realized through different mixing ratios, and the hole transport layer is suitable for a QLED device system with large difference of electron injection and transport change in the process from the initial state of the device to continuous working to the stable state, for example, metal oxide nanoparticles with few surface group connections.

In some embodiments, the hole transport layer is a mixed material layer containing hole transport materials with different energy levels, wherein the mass percentage of the hole transport materials with the absolute value of the top energy level of the valence band less than or equal to 5.3eV is 30-90%; the percentage content of the shallow-level hole transport material is easy to form a hole injection barrier more than or equal to 0.5eV with an outer shell layer of the luminescent material, and in practical application, the mixing proportion of materials with various levels can be flexibly regulated and controlled according to the depth of the energy level of the material. In some embodiments, the hole transport material with the absolute value of the top energy level of the valence band being less than or equal to 5.3eV has good effect when the mass percentage of the hole transport material is 50-60%.

In some embodiments, the hole transport layer is a mixed material layer comprising hole transport materials of different energy levels, wherein at least one hole transport material has a mobility higher than 1 × 10^-3cm²The high mobility of the hole transport material of the embodiment of the application ensures the transport and migration performance of holes, and reduces the influence of the accumulation of the holes on the interface on the device performance. In addition, the top energy level of the valence band of the hole transport layer material with high hole mobility is relatively shallow, and the proper energy range formed between the hole transport layer material and the quantum dot shell material is further ensured.

In some embodiments, the hole transport layer is a mixed material layer comprising hole transport materials of different energy levels, wherein at least one hole transport material has a mobility greater than 1 × 10^-2cm²Vs. In other embodiments, the hole transport layer is a mixed material layer comprising hole transport materials of different energy levels, wherein each hole transport material has a mobility greater than 1 × 10^-3cm²(iv) Vs. According to the embodiments of the present application, mobility of the hole transport material is further optimized, mobility of holes is ensured, influence of charge accumulation on device performance is avoided, and matching of the hole transport material at deep and shallow energy levels in the hole transport layer is ensured, so that an injection barrier of holes is constructed, and formation of Δ E is ensured_EML-HTLAnd the energy level barrier of more than or equal to 0.5eV optimizes the injection balance and recombination efficiency of carriers in the QLED device.

Further, in the examples of the present application, to construct Δ E_EML-HTLThe energy level potential barrier of more than or equal to 0.5eV realizes the purposes of reducing the hole injection rate in the QLED device and regulating the injection and recombination efficiency of carriers, and simultaneously reduces the irreversible damage of the charge accumulation of the HIL and HTL interface to the service life performance of the device. As shown in fig. 5, a fifth aspect of the embodiments of the present application provides an optoelectronic device, in which a hole transport layer of the optoelectronic device includes at least two hole transport materials, and an absolute value of a top valence band energy level of each of the hole transport materials is 5.3eV or less.

The hole transport layer of the photoelectric device provided by the fifth aspect of the present application is a mixture containing a plurality of different valence band top energy level hole transport materialsAnd the valence band top energy level of each hole transport material is less than or equal to 5.3eV, and the energy level difference between the hole transport material and the quantum dot luminescent material with the deeper shell energy level can be greater than or equal to 0.5 eV. The hole injection barrier between quantum dot shell layers in the HTL and the EML is more finely regulated and controlled, so that the delta E of the device_EML-HTLNot less than 0.5 eV. Therefore, after the QLED device enters a stable working state, the optimal charge injection balance and the device efficiency are kept, and the service life of the device is optimized. In addition, by utilizing different hole mobility of the hole transport layer materials with shallow valence band top energy level, the hole mobility of the mixed hole transport layer can be finely regulated and controlled through different mixing ratios.

In some embodiments, the hole transport layer includes a mixed material layer of hole transport materials with different energy levels, wherein the mass percentage of each hole transport material is 5-95%, and the hole transport materials with different energy levels, depths and mobility sizes are mixed and matched, so that the hole mobility and the injection barrier of the mixed hole transport layer are better regulated and controlled.

In some embodiments, the hole transport layer comprises a mixed material layer of hole transport materials of different energy levels, wherein at least one hole transport material has a mobility greater than 1x10^-3cm²The top valence band energy level of the hole transport layer material with high hole mobility is relatively shallow. The mobility of the hole transport material is limited, the high mobility ensures the transport mobility of holes, and simultaneously ensures that a more appropriate injection barrier is formed, thereby avoiding the influence on the device performance caused by the accumulation of the holes on the interface. In some embodiments, the mobility of at least one hole transport material in the hole transport layer is greater than 1 × 10^-2cm²Vs. In some embodiments, the mobility of each hole transport material in the hole transport layer is greater than 1 × 10^-3cm²/Vs。

In some embodiments, when the top valence band energy levels of the hole transport materials in the hole transport layer are all less than or equal to 5.3eV, surface-passivated metal oxide nanoparticles are used in the electron transport layer of the optoelectronic device, preferably the surface is substantially modified. In the embodiments of the present application, when the top valence band energy levels of the hole transport material in the hole transport layer are all less than or equal to 5.3eV, the material with small electron injection and transport changes is suitable for a QLED device system with small difference in electron injection and transport changes from the initial state of the device to the continuous operation to the stable state, for example, metal oxide nanoparticles with fully modified and passivated surfaces.

In the optoelectronic device of the above embodiments of the present application, the hole transport material is selected from: the hole transport materials have the advantages of high hole transport efficiency, good stability, easy acquisition and the like. In the practical application process, a hole transport material with a suitable energy level and mobility can be selected according to the practical application requirements, specifically:

in some embodiments, when a hole material having a top valence band level absolute value of 5.3eV or less is desired in an optoelectronic device, a hole transport material having a top valence band level absolute value of 5.3eV or less may be selected from: at least one of P09 and P13. Wherein the structural formula of P13 is:

the structural formula of P09 is:

in other embodiments, where a hole material having a top valence band energy greater than 5.3eV and less than 5.8eV is desired in an optoelectronic device, a hole transport material having a top valence band energy greater than 5.3eV and less than 5.8eV includes: at least one of TFB, poly-TPD, P11. Wherein the structural formula of P11 is:

the structural formula of poly-TPD is:

the structural formula of TFB is:

in other embodiments, where a hole transport material having a top valence band energy level greater than or equal to 5.8eV in absolute value is desired in an optoelectronic device, a hole transport material having a top valence band energy level greater than or equal to 5.8eV comprises: at least one of P15 and P12. Wherein the structural formula of P12 is:

the structural formula of P15 is:

in some embodiments, the mobility of the hole transport material is greater than 1 × 10^-4cm²and/Vs, the high mobility ensures the transport mobility of holes and reduces the influence of charge accumulation on the service life of the device.

In the embodiments of the present application, the quantum dot material of the core-shell structure includes the outer shell layer, a core, and an intermediate shell layer located between the core and the outer shell layer; wherein the top energy level of the valence band of the core material is shallower than that of the shell material; the top energy level of the valence band of the intermediate shell layer material is between the top energy level of the valence band of the inner core material and the top energy level of the valence band of the outer shell layer material. In the quantum dot material with the core-shell structure, the core material influences the luminous performance, the shell material plays a role in protecting the luminous stability of the core and facilitating carrier injection, the valence band is arranged in an intermediate shell layer between the core and the shell layer, an intermediate transition effect is achieved, carrier injection is facilitated, the intermediate shell layer can form stepped energy level transition from the core to the shell layer on the energy level, and therefore effective injection, effective constraint and reduction of flicker of a crystal lattice interface of carriers are facilitated.

In some embodiments, the shell layer of quantum dot material comprises: at least one of CdS, ZnSe, ZnTe, ZnS, ZnSeS, CdZnS and PbS or at least two of them. The shell layer materials not only protect the luminescence stability of the kernel and facilitate the injection of current carriers into the quantum dot kernel for luminescence, but alsoAnd can form Δ E with HTL layer material_EML-HTLThe energy level barrier of more than or equal to 0.5eV reduces the injection efficiency of holes by improving the hole injection barrier, thereby balancing the injection balance of the holes and electrons in the luminescent layer, improving the luminous efficiency of the device and simultaneously reducing the influence of charge accumulation on the service life of the device.

In some embodiments, the core of quantum dot material comprises: at least one of CdSe, CdZnSe, CdZnS, CdSeS, CdZnSeS, InP, InGaP, GaN, GaP, ZnSe, ZnTe, ZnTeSe. The luminescent property of the quantum dot material is related to that of the core material, the materials ensure that the QLED device can emit light in a visible light range of 400-700 nm, the range required by the application of a photoelectric display device is met, and the beneficial effect of the mutual relationship of the energy levels of the materials can be better embodied.

In some embodiments, the intermediate shell material is selected from: at least one of CdZnSe, ZnSe, CdZnS, CdZnSeS, CdS, and CdSeS. In the specific embodiment of the application, the intermediate shell layer is selected to form continuous and natural transition of the components from the inner core to the outer layer on the components, so that the minimum lattice mismatch and the minimum lattice defects among the inner core, the intermediate shell layer and the outer shell layer are facilitated, and the optimal luminescence performance of the core-shell quantum dot material is realized.

In some embodiments, the wavelength range of the light-emitting peak of the quantum dot material is 400-700 nm, on one hand, the wavelength range is a range required by application of a photoelectric display device, and on the other hand, the beneficial effect of the light-emitting layer in the device realized by the energy level correlation in the wavelength range can be better embodied.

In some embodiments, the thickness of the shell layer of the quantum dot material is 0.2-6.0 nm, and the thickness covers the thickness of a conventional shell, so that the quantum dot material can be widely applied to QLED devices of different systems. If the thickness of the shell layer is too large, the rate of injecting carriers into the luminescent quantum dots through the tunneling effect is reduced; when the thickness of the shell layer is too small, the shell material cannot play a sufficient protection role and passivation role on the core material, and the luminescence performance and stability of the quantum dot material are influenced.

In the above embodiments of the present application, the optoelectronic device further comprises an electron transport layer, and the electron transport material in the electron transport layer is selected from: at least one of a metal-oxygen group compound transmission material and an organic transmission material. The metal oxide material generally has high electron mobility, and can be prepared into a thin film in a QLED device by a solution method or a vacuum sputtering method. The organic electron transport layer material can realize the regulation and control of energy level in a wider range, and can be prepared into a thin film in a QLED device in a vacuum evaporation mode or a solution method; the solution method includes inkjet printing, spin coating, jet printing, slit coating, screen printing, or the like. And a more appropriate electron transport material can be flexibly selected according to the actual application requirements.

In some embodiments, the metal chalcogenide delivery material is selected from: at least one of zinc oxide, titanium oxide, zinc sulfide and cadmium sulfide. The metal oxygen group compound transmission materials adopted in the embodiment of the application have higher electron transfer efficiency. In some embodiments, to further improve the efficiency of electron transfer, the metal-oxygen compound transport material is selected from: at least one of zinc oxide, titanium oxide, zinc sulfide and cadmium sulfide which are doped with metal elements, wherein the metal elements comprise at least one of aluminum, magnesium, lithium, lanthanum, yttrium, manganese, gallium, iron, chromium and cobalt, and the metal elements can further improve the electron transfer efficiency of the material.

In some embodiments, the particle size of the metal oxygen group compound transmission material is less than or equal to 10nm, on one hand, the metal oxygen group compound transmission material with small particle size is more favorable for depositing to obtain an electron transmission layer film with a compact film layer and uniform thickness, so that the bonding tightness of the electron transmission layer film and an adjacent functional layer is improved, the interface resistance is reduced, and the device performance is more favorable for improving. On the other hand, the band gap of the metal oxygen group compound transmission material with small particle size is wider, exciton luminescence quenching of the quantum dot material is reduced, and device efficiency is improved.

In some embodiments, the electron mobility of the metal chalcogenide transport material is 10^-2～10^-3cm²Vs, a high mobility electron transport material capable of reducing charge accumulation in the interface layer and increasing electron injectionAnd (3) input and composite efficiency.

In some embodiments, the organic transport material has an electron mobility of not less than 10^-4cm²(iv) Vs. In some embodiments, the organic transport material is selected from: 8-Hydroxyquinoline-lithium (Alq)₃) At least one of aluminum octahydroxyquinoline, fullerene derivative PCBM, 3, 5-bis (4-tert-butylphenyl) -4-phenyl-4H-1, 2, 4-triazole (BPT), and 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene (TPBi). The organic transmission materials can realize the regulation and control of energy levels in a wider range, are more beneficial to regulating and controlling the energy levels of all functional layers of the device, and improve the stability and the photoelectric conversion efficiency of the device.

In some embodiments, the electron transport layer is a laminated composite structure including at least two sub-electron transport layers, and by selecting sub-electron transport layers with different transport migration efficiencies and energy level regulation characteristics, the electronic transport layer properties can be regulated more flexibly, so that the device performance can be optimized better.

In some embodiments, the material of at least one sub-electron transport layer of the electron transport layers is a metal-oxygen group compound transport material. In some embodiments, all of the electron transport layers in the electron transport layer are metal oxides, and the metal oxide materials of different electron transport layers may be the same or different. That is, among the multi-layer electron transport layer in which all the sub electron transport layers are metal oxides, there may be a sub electron transport layer including at least one layer of metal oxide nanoparticles and at least one layer of non-nanoparticle type metal oxide sub electron transport layer. The sub-electron transport layers may also be doped and intrinsic metal oxides (e.g., Mg doped ZnO + intrinsic ZnO), respectively. The electron transport layers can also be all the same metal oxide nanoparticles. When the electron transport layers are all the same metal oxide nanoparticles, the electron mobility of different electron transport layers can be the same or different.

In some embodiments, the material of at least one of the electron transport layers is an organic transport material. In some embodiments, in the electron transport layers, the material of at least one sub-electron transport layer is a metal-oxygen group compound transport material, the material of at least one sub-electron transport layer is an organic transport material, and the metal oxide materials of different sub-electron transport layers can be the same or different; the metal oxide material is preferably nanoparticles of the corresponding metal oxide. The electron transport layer has high electron mobility and flexibility of energy level matching simultaneously through the co-blending action of the metal oxygen group compound transport material and the organic transport material in the electron transport layer. The energy level and the electron mobility of the electron transport layer are effectively regulated, so that the electron transport layer is fully matched with the hole injection. In some embodiments, the electron transport layer including the plurality of sub-electron transport layers may be a stacked composite structure of a combination of ZnO nanoparticles + NaF, a combination of Mg-doped ZnO nanoparticles + NaF, or the like.

In the quantum dot material with the core-shell structure, the core material influences the luminescence property of the quantum dot material, and the shell material plays a role in protection and is beneficial to carrier injection. After the shell layer material is determined, the valence band top energy level difference between the shell layer material of the quantum dot material and the hole transport material can be larger than or equal to 0.5eV by adjusting the shell layer thickness, the valence band top energy level of the hole transport material and the like, namely an expected injection barrier is constructed, and E_EML-HTLNot less than 0.5eV, the balance of the injection efficiency of electrons and holes in the luminescent layer is optimized, the efficiency of the device is improved, and the service life of the device is prolonged.

Further, as shown in fig. 6, a sixth aspect of the present embodiment provides an optoelectronic device, including a quantum dot light-emitting layer and a hole transport layer, where the quantum dot light-emitting layer includes a quantum dot material with a core-shell structure, an outer shell layer of the quantum dot material is ZnSe, and an absolute value of a top valence band energy level of the hole transport material in the hole transport layer is less than or equal to 5.4 eV.

According to the photoelectric device provided by the sixth aspect of the application, on the premise that the outer shell layer of the quantum dot material is ZnSe, the optimal structure of the photoelectric device is designed according to the characteristics of ZnSe such as the energy level and the like. Specifically, since the valence band energy level of the ZnSe envelope material is relatively shallow (the absolute value of the energy level is small), if the valence band top energy level difference (Δ E) is to be constructed_EML-HTL) If the hole injection barrier is 0.5eV or more, the absolute value of the top valence band energy of the hole transport material should be 5.4eV or less.At this time,. DELTA.E_EML-HTLThe electron injection barrier is not less than 0.5eV, the hole injection barrier is constructed, the hole injection rate is reduced, the injection efficiency of electron holes in the light-emitting layer is balanced, the carrier accumulation is reduced, and the light-emitting efficiency is improved.

In some embodiments, the ZnSe shell layer in the quantum dot material has a thickness of 2-5 nm. According to the embodiment of the application, the band gap of ZnSe is relatively narrow, the constraint capacity on excitons in the quantum dot core is relatively poor, in order to ensure the good luminous efficiency of the quantum dot core luminescent material, the thicker ZnSe shell layer thickness is required to be used, and the preferred shell layer thickness is 2.0-5.0 nanometers. If the thickness of the shell layer is too large, the rate of injecting carriers into the luminescent quantum dots through the tunneling effect is reduced; when the thickness of the shell layer is too small, the rate of injecting the current carrier into the luminescent quantum dot through the tunneling effect is increased, but when the thickness of the shell layer is small to a certain degree, the shell layer structure cannot play a sufficient role in protecting and passivating the core, so that the luminescent performance and stability of the quantum dot material are influenced.

In some embodiments, the quantum dot material has a peak emission wavelength of 510-640 nm. For blue core-shell quantum dots with short emission wavelength and wide quantum dot core band gap, the emission efficiency of the quantum dot material can not be fully ensured even if a thick ZnSe shell layer is used, so that the preferred quantum dot emission material in the embodiment of the application is red or green quantum dots with emission peak wavelength range of 510-640 nanometers, and the emission efficiency of the quantum dots is better ensured.

In some embodiments, the difference between the valence band top energy levels of the ZnSe material and the hole transport material is 0.5-1.0 eV. In the embodiment of the application, the ZnSe shell layer has a thicker preferred thickness, so that the rate of injecting carriers into the luminescent quantum dots through a tunneling effect is weakened, and the valence band top energy level difference (Delta E) of the corresponding hole transport layer material and the corresponding quantum dot shell layer material is reduced_EML-HTL) The range of 0.5-1.0 eV is selected. If Δ E_EML-HTLIf the size of the quantum dot material is too large, the efficiency of injecting holes into the luminescent core of the quantum dot is further reduced, and the luminous efficiency of the quantum dot material is influenced.

In some embodiments, the absolute value of the top valence band energy level of the hole transport material is preferably 4.9eV to 5.4eV, and in this range, a more suitable hole injection barrier can be constructed with the ZnSe shell material to optimize carrier injection and recombination efficiency in the light emitting layer.

In some embodiments, the absolute value of the top valence band energy level of the hole transport material is preferably 4.9eV to 5.4eV, and the difference between the top valence band energy levels of the ZnSe material and the hole transport material is 0.5eV to 1.0 eV.

In some embodiments, the hole transport material has a mobility greater than 1 × 10^-3cm²The absolute value of the top valence band energy level of the hole transport material adopted in the embodiment of the application is less than or equal to 5.4eV, the energy level is shallow, and the hole transport layer material with the shallow top valence band energy level generally has high hole mobility, so that holes can be effectively transported in a hole transport layer film with a certain thickness, the overall resistance of the device is reduced, the driving voltage of the device is reduced, and the service life of the device is prolonged.

Further, as shown in fig. 7, a seventh aspect of the embodiments of the present application provides an optoelectronic device, including a quantum dot light-emitting layer and a hole transport layer, where the quantum dot light-emitting layer includes a quantum dot material with a core-shell structure, an outer shell layer of the quantum dot material is ZnS, and an absolute value of a top valence band energy level of the hole transport material in the hole transport layer is less than or equal to 6.0 eV.

According to the photoelectric device provided by the seventh aspect of the present application, on the premise that the shell layer of the quantum dot material is specifically ZnS, the preferable structure of the photoelectric device is designed according to the characteristics of ZnS, such as the energy level and the like. Specifically, the valence band energy level of the ZnS shell material is deep (the absolute value of the energy level is larger relative to ZnSe), and the valence band top energy level difference (Δ E) is constructed_EML-HTL) When the valence band top energy level is not less than 0.5eV, the valence band top energy level of the hole transport material may be not more than 6.0 eV. At this time,. DELTA.E_EML-HTLThe electron injection barrier is not less than 0.5eV, the hole injection barrier is constructed, the hole injection rate is reduced, the injection efficiency of electron holes in the light-emitting layer is balanced, the carrier accumulation is reduced, and the light-emitting efficiency is improved.

In some embodiments, the ZnS shell layer has a thickness of 0.2 to 2.0 nm. According to the embodiment of the application, the band gap of ZnS is wide, so that the binding capacity of the ZnS to excitons in the quantum dot core is strong, the good luminous efficiency of the quantum dot luminous material can be basically ensured by adopting the thin ZnS shell layer thickness, and the preferred shell layer thickness is 0.2-2.0 nanometers. Meanwhile, the thin ZnS shell can effectively reduce the overall resistance of the device and reduce the driving voltage of the device, thereby improving the performance of the device.

In some embodiments, the absolute value of the top valence band energy level of the hole transport material is preferably 4.9eV to 6.0eV, which can form a more suitable hole injection barrier with the ZnS shell material to optimize carrier injection and recombination efficiency in the light emitting layer. In some embodiments, the absolute value of the top valence band energy level of the hole transport material is preferably from 4.9eV to 5.5 eV.

In some embodiments, the difference between the valence band top energy levels of the ZnS material and the hole transport material is 1.0-1.6 eV. In the embodiment of the application, the ZnS shell layer has a relatively thin preferred thickness, so that the rate of injecting carriers into the luminescent quantum dots through a tunneling effect is increased, and the valence band top energy level difference (Delta E) between the corresponding hole transport layer material and the quantum dot shell layer material in the quantum dot luminescent layer is increased_EML-HTL) An appropriate increase is required to better balance the injection balance of holes and electrons, and a preferred range thereof should be between 1.0-1.6 eV. If Δ E_EML-HTLIf the size of the quantum dot material is not too large, the efficiency of injecting holes into the quantum dot light-emitting core is further reduced, and the light-emitting efficiency of the quantum dot material is influenced.

In some embodiments, the quantum dot material has a peak emission wavelength of 400-700 nm. According to the embodiment of the application, the band gap of ZnS is wide, so that the binding capacity of the ZnS to excitons in the quantum dot core is strong, the luminous efficiency of a quantum dot material can be effectively ensured, the ZnS quantum dot material is suitable for all quantum dot materials in a visible light area with the luminous peak wavelength of 400-700 nm, and the application range is wide.

In some embodiments, the hole mobility is relatively low due to the deep top valence band energy level (less than or equal to 6.0eV) of the hole transport material used in the embodiments of the present application, and the mobility of the hole transport material is higher than 1 × 10^-4cm²Vs. In some embodiments, the hole transport material has a mobility greater than 1 × 10^-3cm²/Vs。

Further, as shown in fig. 8, an eighth aspect of the present application provides a photoelectric device, including a quantum dot light-emitting layer and a hole transport layer, where the quantum dot light-emitting layer includes a quantum dot material with a core-shell structure, an outer shell layer of the quantum dot material is CdZnS, and an absolute value of a top valence band energy level of the hole transport material in the hole transport layer is less than or equal to 5.9 eV.

The photoelectric device that this application eighth aspect provided, under the prerequisite that the shell layer of quantum dot material specifically is CdZnS, according to characteristics such as CdZnS's energy level, designed photoelectric device's preferred structure. Specifically, since the shell layer of the quantum dot in this embodiment uses CdZnS, and the valence band level is between ZnSe and ZnS, in order to construct a hole injection barrier with a valence band top level difference (Δ EEML-HTL) greater than or equal to 0.5eV, the valence band top level of the hole transport material needs to be less than or equal to 5.9 eV. The hole injection barrier is constructed, so that the hole injection rate is reduced, the injection efficiency of electron holes in the light-emitting layer is balanced, the accumulation of carriers is reduced, and the light-emitting efficiency is improved.

In some embodiments, the CdZnS shell layer has a thickness of 0.5-3.0nm, and since the CdZnS has a band gap between ZnSe and ZnS, the preferred shell layer has a thickness of 0.5-3.0nm, which can simultaneously ensure the binding capability to excitons in the quantum dot core and the good luminous efficiency of the quantum dot luminescent material itself.

In some embodiments, the absolute value of the valence band top energy level of the hole transport material is 4.9-5.9 eV, and a more appropriate hole injection barrier can be constructed with the CdZnS shell material in the range, so that the carrier injection and recombination efficiency in the light emitting layer is optimized. In some embodiments, the absolute value of the top valence band energy level of the hole transport material is 4.9-5.5 eV.

In some embodiments, the difference between the valence band top energy levels of the CdZnS material and the hole transport material is 0.8-1.4 eV. The valence band top energy level difference (Delta E) between the hole transport layer material and the quantum dot shell layer material in the quantum dot light-emitting layer in the embodiment of the application_EML-HTL) The optimal range is 0.8-1.4eV, the injection efficiency of carriers to a luminous quantum dot through a tunneling effect can be guaranteed, and the injection efficiency of holes and electrons can be well balanced. If Δ E_EML-HTLIf the size is too large, the efficiency of injecting carriers into the luminescent quantum dot core through the tunneling effect is reduced; if Δ E_EML-HTLIf the injection rate is too small, the injection rate of holes is not adjusted well.

In some embodiments, the quantum dot material has a peak emission wavelength of 400-700 nm. According to the embodiment of the application, the binding capacity of CdZnS to excitons in the quantum dot core is relatively strong, the luminous efficiency of the quantum dot material can be effectively ensured, the quantum dot material is suitable for all quantum dot materials in a visible light area with the luminous peak wavelength of 400-700 nm, and the application range is wide.

In some embodiments, the hole mobility is relatively low due to the deep top valence band energy level (less than or equal to 5.9eV) of the hole transport material used in the embodiments of the present application, and the mobility of the hole transport material is higher than 1 × 10^-4cm²Vs. In some embodiments, the hole transport material has a mobility greater than 1 × 10^-3cm²/Vs。

Further, as shown in fig. 9, a ninth aspect of the present application provides a photoelectric device, including a quantum dot light emitting layer and a hole transport layer, where the quantum dot light emitting layer includes a quantum dot material with a core-shell structure, an outer shell layer of the quantum dot material is ZnSeS, and an absolute value of a top valence band energy level of the hole transport material in the hole transport layer is less than or equal to 5.7 eV.

According to the photoelectric device provided by the ninth aspect of the application, on the premise that the outer shell layer of the quantum dot material is ZnSeS, the optimal structure of the photoelectric device is designed according to the characteristics of the ZnSeS such as the energy level and the like. Specifically, since the envelope layer of the quantum dot in this embodiment adopts ZnSeS, and the valence band energy level is between ZnSe and ZnS, in order to construct a hole injection barrier with a valence band top energy level difference (Δ EEML-HTL) greater than or equal to 0.5eV, the valence band top energy level of the hole transport material needs to be less than or equal to 5.7 eV. The hole injection barrier is constructed, so that the hole injection rate is reduced, the injection efficiency of electron holes in the light-emitting layer is balanced, the accumulation of carriers is reduced, and the light-emitting efficiency is improved.

In some embodiments, the thickness of the ZnSeS shell layer is 1.0-4.0 nm, and since Se in the ZnSeS shell which is easily oxidized is closer to the surface of the quantum dot, the ZnSeS shell needs to be thicker to ensure sufficient protection and passivation for the inner core, so that the thickness of the ZnSeS shell layer is preferably 1.0-4.0 nm.

In some embodiments, the absolute value of the valence band top energy level of the hole transport material is 4.9-5.7 eV, and a more appropriate hole injection barrier can be constructed with the ZnSeS shell material within the range, so that the carrier injection and recombination efficiency in the light emitting layer is optimized. In some embodiments, the absolute value of the top valence band energy level of the hole transport material is 4.9-5.4 eV.

In some embodiments, the difference between the valence band top energy levels of the ZnSeS material and the hole transport material is 0.9-1.4 eV. The valence band top energy level difference (Delta E) between the hole transport layer material and the quantum dot shell layer material in the quantum dot light-emitting layer in the embodiment of the application_EML-HTL) When the optimal range is 0.9-1.4eV, the injection efficiency of the carriers to the luminescent quantum dots through the tunneling effect can be guaranteed, and the injection efficiency of holes and electrons can be well balanced. If Δ E_EML-HTLIf the size is too large, the efficiency of injecting carriers into the luminescent quantum dot core through the tunneling effect is reduced; if Δ E_EML-HTLIf the injection rate is too small, the injection rate of holes is not adjusted well.

In some embodiments, the quantum dot material has a peak emission wavelength of 400-700 nm. According to the embodiment of the application, the binding capacity of ZnSeS to excitons in the quantum dot core is relatively strong, the luminous efficiency of the quantum dot material can be effectively ensured, the ZnSeS quantum dot material is suitable for all quantum dot materials in a visible light region with the luminous peak wavelength of 400-700 nm, and the application range is wide.

In some embodiments, the hole mobility is relatively low due to the deep top valence band energy level (less than or equal to 5.7eV) of the hole transport material used in the embodiments of the present application, and the mobility of the hole transport material is higher than 1 × 10^-4cm²Vs. In some embodiments, the hole transport material has a mobility greater than 1 × 10^-3cm²/Vs。

The above sixth to ninth aspects of the present application provide that in the optoelectronic device, the hole transport material is selected from: in practical application, the hole transport material with appropriate mobility can be selected according to specific application requirements.

In some embodiments, the aniline group-containing polymer having an absolute value of a top valence band energy level of the hole transport material of 5.4eV or less comprises: poly-TPD, P9, TFB, P13.

In some embodiments, a copolymer containing a fluorene group and an aniline group having an absolute value of a top valence band energy level of a hole transport material of 5.4eV or less includes: TFB, P13.

In some embodiments, a polymer comprising an aniline group with an absolute value of the top valence band energy level of the hole transport material greater than 5.4eV and less than or equal to 5.9eV comprises: p11, P12 and P15.

In some embodiments, a copolymer containing a fluorene group and an aniline group having an absolute value of a top valence band energy level of greater than 5.4eV and less than or equal to 5.9eV of a hole transport material comprises: p12, P15.

In the optoelectronic device provided in the sixth to ninth aspects of the present application, the quantum dot material of the core-shell structure includes the outer shell layer, a core, and an intermediate shell layer located between the core and the outer shell layer; wherein the top energy level of the valence band of the core material is shallower than that of the shell material; the top energy level of the valence band of the intermediate shell layer material is between the top energy level of the valence band of the inner core material and the top energy level of the valence band of the outer shell layer material.

In some embodiments, the core material is selected from: at least one of the group II-IV, group II-VI, group II-V, group III-VI, group IV-VI, group I-III-VI, group II-IV-VI and group II-IV-V semiconductor compounds of the periodic table of elements. In some embodiments, the core material is selected from: at least one of CdSe, CdZnSe, CdSeS, CdZnSeS, InP, InGaP, GaP, ZnTe and ZnTeSe. The core materials have good luminescence performance and have good matching effect with the outer shell layer of ZnSe, ZnS, CdZnS or ZnSeS.

In some embodiments, the intermediate shell material is selected from the group consisting of: at least one of CdZnSe, ZnSe, CdZnS, CdZnSeS, CdS, and CdSeS. The collocation principle of the intermediate shell layer in the embodiment of the application is as follows: the intermediate shell layer preferably forms continuous natural transition from the inner core to the outer layer in composition, so that the minimum lattice mismatch and the minimum lattice defect among the inner core, the intermediate shell layer and the outer shell layer are facilitated, and the optimal luminescence performance of the core-shell quantum dot material is realized; the intermediate shell layer generally needs to form a step-shaped energy level transition from the inner core to the outer shell layer in energy level, so that the effective injection of carriers, the effective binding and the reduction of the flicker of crystal lattice interfaces are realized.

The sixth to ninth aspects of the present application provide that, in the optoelectronic device, the optimization of the hole injection functional layer in the optoelectronic device according to the second or third aspects may be combined, and the optoelectronic device may include a first hole injection layer, and an absolute value of a difference between a work function of a first hole injection material of the first hole injection layer and a top energy level of a valence band of a hole transport material is less than or equal to 0.2 eV. Or the difference between the top energy level of the valence band of the material of the second hole injection layer and the work function of the second hole injection material in the second hole injection layer is less than-0.2 eV. The hole utilization rate in the device is further improved, the hole injection rate is finely regulated, the injection of carriers in the device is balanced, and the recombination efficiency is improved; meanwhile, the influence of interface layer charge accumulation on the service life of the device is reduced.

The sixth to ninth aspects of the present application provide that the optoelectronic device further includes an electron transport layer, where the electron transport layer includes at least two sub-electron transport layers stacked in layers; wherein, the material of at least one layer of the electron transport layer is a metal oxygen group compound transport material. Or, the material of at least one sub-electron transport layer is an organic transport material. Or, the material at least comprising one sub electron transport layer is a metal oxygen group compound transport material and the material of one sub electron transport layer is an organic transport material.

Further, as shown in fig. 10, a tenth aspect of the present application provides a photovoltaic device, including a quantum dot light emitting layer and a hole transport layer, where the quantum dot light emitting layer includes a quantum dot material with a core-shell structure, an outer shell layer of the quantum dot material is ZnSe, and a mobility of the hole transport material in the hole transport layer is higher than 1 × 10^-3cm²/Vs。

The photoelectric device provided by the tenth aspect of the present application is characterized by ZnSeThe valence band energy level of the shell material is relatively shallow (the absolute value of the energy level is small), the band gap is relatively narrow, the constraint capacity of excitons in the quantum dot core-shell structure is relatively poor, in order to ensure the good luminous efficiency of the quantum dot luminous material, the thickness of the thick ZnSe shell layer needs to be used, and the injection rate of the ZnSe shell layer to the luminous quantum dot through the tunneling effect is weakened. Quantum dot layer with ZnSe envelope layer to satisfy the structure of hole injection barrier between HTL and quantum dot envelope layer in EML, E_EML-HTLNot less than 0.5eV, and higher than 1 × 10 by matching with HTL material with high hole mobility^{- 3}cm²the/Vs compensates the influence of the tunneling effect on the hole injection rate, balances the injection efficiency of electron holes in the light-emitting layer, reduces the accumulation of carriers and improves the light-emitting efficiency.

In some embodiments, the ZnSe shell layer in the quantum dot material has a thickness of 2-5 nm. According to the embodiment of the application, the band gap of ZnSe is relatively narrow, the constraint capacity on excitons in the quantum dot core is relatively poor, in order to ensure the good luminous efficiency of the quantum dot core luminescent material, the thicker ZnSe shell layer thickness is required to be used, and the preferred shell layer thickness is 2.0-5.0 nanometers. If the thickness of the shell layer is too large, the rate of injecting carriers into the luminescent quantum dots through the tunneling effect is reduced; when the thickness of the shell layer is too small, the rate of injecting the current carrier into the luminescent quantum dot through the tunneling effect is increased, but when the thickness of the shell layer is too small, the shell layer structure cannot play a sufficient role in protecting and passivating the core, so that the luminescent performance and stability of the quantum dot material are influenced.

In some embodiments, the quantum dot material has a peak emission wavelength of 510-640 nm. For blue core-shell quantum dots with short luminescence wavelength and wide quantum dot core band gap, the luminous efficiency of the quantum dot material can not be fully ensured even if a thick ZnSe shell layer is used, so that the preferred quantum dot luminescent material in the embodiment of the application is red or green quantum dots with the luminescence peak wavelength range of 510-640 nanometers, and the luminous efficiency of the quantum dots is better ensured.

In some embodiments, the difference between the valence band top energy levels of the ZnSe material and the hole transport material is 0.5-1.0 eV. Book (I)The application example has the advantages that the ZnSe shell layer has a thicker preferred thickness, so that the injection rate of carriers to a luminous quantum dot through a tunneling effect is weakened, and the valence band top energy level difference (delta E) of a corresponding hole transport layer material and a corresponding quantum dot shell layer material is reduced_EML-HTL) It is not preferred to be too large, and the preferable range is 0.5-1.0 eV. If Δ E_EML-HTLIf the size of the quantum dot material is not too large, the efficiency of injecting holes into the quantum dot light-emitting core is further reduced, and the light-emitting efficiency of the quantum dot material is influenced.

In some embodiments, the absolute value of the top valence band energy level of the hole transport material is preferably 4.9eV to 5.4eV, and in this range, a more suitable hole injection barrier can be constructed with the ZnSe shell material to optimize carrier injection and recombination efficiency in the light emitting layer.

Further, as shown in fig. 11, an eleventh aspect of the present embodiment provides an optoelectronic device, including a quantum dot light emitting layer and a hole transport layer, where the quantum dot light emitting layer includes a quantum dot material with a core-shell structure, an outer shell layer of the quantum dot material is ZnS, and a mobility of the hole transport material in the hole transport layer is higher than 1 × 10^-4cm²/Vs。

According to the photoelectric device provided by the eleventh aspect of the application, when the quantum dot shell material adopts ZnS, because the band gap of ZnS is wide, the binding capacity of excitons in the quantum dot core-shell structure is strong, the good luminous efficiency of the quantum dot luminous material can be basically ensured by adopting the thin ZnS shell layer thickness, and therefore the rate of injecting carriers into luminous quantum dots through a tunneling effect is enhanced. The hole transport material has a hole mobility of 1 × 10 or more^-4cm²the/Vs is a hole injection barrier with the valence band top energy level difference of more than or equal to 0.5eV between the shell layer material and the hole transport material for constructing the quantum dot material, and the E_EML-HTLNot less than 0.5eV, and ensures the efficiency of hole transmission and injection into the quantum dot material.

In some embodiments, the ZnS shell layer has a thickness of 0.2 to 2.0 nm. According to the embodiment of the application, the band gap of ZnS is wide, so that the binding capacity of the ZnS to excitons in the quantum dot core is strong, the good luminous efficiency of the quantum dot luminous material can be basically ensured by adopting the thin ZnS shell layer thickness, and the preferred shell layer thickness is 0.2-2.0 nanometers. Meanwhile, the thin ZnS shell can effectively reduce the overall resistance of the device and reduce the driving voltage of the device, thereby improving the performance of the device.

In some embodiments, the absolute value of the top valence band energy level of the hole transport material is preferably 4.9eV to 6.0eV, which can form a more suitable hole injection barrier with the ZnS shell material to optimize carrier injection and recombination efficiency in the light emitting layer. In some embodiments, the absolute value of the top valence band energy level of the hole transport material is preferably from 4.9eV to 5.5 eV.

In some embodiments, the difference between the valence band top energy levels of the ZnS material and the hole transport material is 1.0-1.6 eV. In the embodiment of the application, the ZnS shell layer has a relatively thin preferred thickness, so that the rate of injecting carriers into the luminescent quantum dots through a tunneling effect is increased, and thus, the valence band top energy level difference (Δ E) between the corresponding hole transport layer material and the quantum dot shell layer material in the quantum dot luminescent layer is increased_EML-HTL) It needs to be increased appropriately to better balance the injection balance of holes and electrons, and the preferable range is 1.0-1.6 eV. If Δ E_EML-HTLIf the size of the quantum dot material is not too large, the efficiency of injecting holes into the quantum dot light-emitting core is further reduced, and the light-emitting efficiency of the quantum dot material is influenced.

In some embodiments, the quantum dot material has a peak emission wavelength of 400-700 nm. According to the embodiment of the application, the band gap of ZnS is wide, so that the binding capacity of the ZnS to excitons in the quantum dot core is strong, the luminous efficiency of a quantum dot material can be effectively ensured, the ZnS quantum dot material is suitable for all quantum dot materials in a visible light area with the luminous peak wavelength of 400-700 nm, and the application range is wide.

In some embodiments, the hole transport material has a mobility greater than 1 × 10^-3cm²/Vs。

Further, as shown in fig. 12, a twelfth aspect of the embodiments of the present application provides an optoelectronic device, including a quantum dot light-emitting layer and a hole transport layer, where the quantum dot light-emitting layer includes a quantum dot material with a core-shell structure, an outer shell layer of the quantum dot material is CdZnS, and a migration of the hole transport material in the hole transport layerThe rate is higher than 1x10^-4cm²/Vs。

In the photoelectric device provided by the twelfth aspect of the application, the shell layer of the quantum dot adopts CdZnS, the band gap width of the CdZnS is between ZnSe and ZnS, the binding capability of excitons in the quantum dot core-shell structure is moderate, and the good luminous efficiency of the quantum dot luminescent material can be basically ensured by the relatively moderate CdZnS shell layer thickness, so that the influence of the shell layer thickness on the tunneling effect of a current carrier is small. Meanwhile, the valence band energy level of the CdZnS shell material is between ZnSe and ZnS, and the valence band top energy level difference (Delta E) needs to be constructed_EML-HTL) A hole injection barrier of 0.5eV or more requires a hole transport material having a relatively shallow top valence band energy. Therefore, the hole mobility of the HTL material is 1 × 10 or more^-4cm²When Vs, the construction of Δ E can be satisfied simultaneously_EML-HTLThe hole injection barrier is more than or equal to 0.5eV, and the efficiency of injecting the hole into the quantum dot material is ensured.

In some embodiments, the CdZnS shell layer has a thickness of 0.5-3.0nm, and since the CdZnS has a band gap between ZnSe and ZnS, the preferred shell layer has a thickness of 0.5-3.0nm, which can simultaneously ensure the binding capability to excitons in the quantum dot core and the good luminous efficiency of the quantum dot luminescent material itself.

In some embodiments, the absolute value of the valence band top energy level of the hole transport material is 4.9-5.9 eV, and a more appropriate hole injection barrier can be constructed with the CdZnS shell material in the range, so that the carrier injection and recombination efficiency in the light emitting layer is optimized. In some embodiments, the absolute value of the top valence band energy level of the hole transport material is 4.9-5.5 eV.

In some embodiments, the difference between the valence band top energy levels of the CdZnS material and the hole transport material is 0.8-1.4 eV. The valence band top energy level difference (Delta E) between the hole transport layer material and the quantum dot shell layer material in the quantum dot light-emitting layer in the embodiment of the application_EML-HTL) The optimal range is 0.8-1.4eV, the injection efficiency of carriers to a luminous quantum dot through a tunneling effect can be guaranteed, and the injection efficiency of holes and electrons can be well balanced. If Δ E_EML-HTLToo large, the efficiency of carrier injection into the luminescent quantum dot nuclei by tunneling effectDecrease; if Δ E_EML-HTLIf the injection rate is too small, the injection rate of holes is not adjusted well.

In some embodiments, the quantum dot material has a peak emission wavelength of 400-700 nm. The embodiment of the application has the advantages that the binding capacity of the CdZnS to excitons in the quantum dot core is relatively strong, the luminous efficiency of the quantum dot material can be effectively guaranteed, the quantum dot material is suitable for all quantum dot materials in a visible light area with the luminous peak wavelength of 400-700 nm, and the application range is wide.

In some embodiments, the hole transport material has a mobility greater than 1 × 10^-3cm²/Vs。

Further, as shown in fig. 13, a thirteenth aspect of the embodiments of the present application provides an optoelectronic device, including a quantum dot light emitting layer and a hole transport layer, where the quantum dot light emitting layer includes a quantum dot material with a core-shell structure, an outer shell layer of the quantum dot material is ZnSeS, and a mobility of the hole transport material in the hole transport layer is higher than 1 × 10^-4cm²/Vs。

In the photoelectric device provided by the thirteenth aspect of the application, the outer shell layer of the quantum dot adopts ZnSeS, the band gap width of the ZnSeS is between ZnSe and ZnS, the binding capability to excitons in the quantum dot core-shell structure is moderate, and the influence of the outer shell layer on the tunneling effect of carriers is small. Meanwhile, the valence band energy level of the ZnSeS shell material is between ZnSe and ZnS, and the valence band top energy level difference (Delta E) is constructed_EML-HTL) A hole injection barrier of 0.5eV or more requires a hole transport material having a relatively shallow top valence band energy. Therefore, the hole mobility of the HTL material is 1 × 10 or more^-4cm²And when the material is/Vs, the requirements of constructing a hole injection barrier and ensuring the efficiency of hole transmission injection into the quantum dot material can be met simultaneously.

In some embodiments, the thickness of the ZnSeS shell layer is 1.0-4.0 nm, and since Se in the ZnSeS shell which is easily oxidized is closer to the surface of the quantum dot, the ZnSeS shell needs to be thicker to ensure sufficient protection and passivation for the inner core, so that the thickness of the ZnSeS shell layer is preferably 1.0-4.0 nm.

In some embodiments, the absolute value of the valence band top energy level of the hole transport material is 4.9-5.7 eV, and a more appropriate hole injection barrier can be constructed with the ZnSeS shell material within the range, so that the carrier injection and recombination efficiency in the light emitting layer is optimized. In some embodiments, the absolute value of the top valence band energy level of the hole transport material is 4.9-5.4 eV.

In some embodiments, the difference between the valence band top energy level of the ZnSeS material and the valence band top energy level of the hole transport material is 0.9-1.4 eV. The valence band top energy level difference (Delta E) between the hole transport layer material and the quantum dot shell layer material in the quantum dot light-emitting layer in the embodiment of the application_EML-HTL) When the optimal range is 0.9-1.4eV, the injection efficiency of the carriers to the luminous quantum dots through the tunneling effect can be guaranteed, and the injection efficiency of holes and electrons can be well balanced. If Δ E_EML-HTLIf the size is too large, the efficiency of injecting carriers into the luminescent quantum dot core through the tunneling effect is reduced; if Δ E_EML-HTLIf the injection rate is too small, the injection rate of holes is not adjusted well.

In some embodiments, the quantum dot material has a peak emission wavelength of 400-700 nm. According to the embodiment of the application, the binding capacity of ZnSeS to excitons in the quantum dot core is relatively strong, the luminous efficiency of the quantum dot material can be effectively ensured, the ZnSeS quantum dot material is suitable for all quantum dot materials in a visible light region with the luminous peak wavelength of 400-700 nm, and the application range is wide.

In some embodiments, the hole transport material has a mobility greater than 1 × 10^-3cm²/Vs。

The above tenth to thirteenth aspects of the present application provide the optoelectronic device wherein the hole transport material is selected from: in practical application, the hole transport material with appropriate mobility can be selected according to specific application requirements.

In some embodiments, the hole transport material has a mobility greater than 1 × 10^-3cm²Aniline group containing polymers of/Vs include: poly-TPD, TFB, P9, P11, P13.

In some embodiments, the hole transport material has a mobility greater than 1 × 10^-3cm²Copolymers containing fluorene and aniline groups of/Vs include: TFB, P13.

In some embodiments, the hole transport material has a mobility greater than 1 × 10^-4cm²Aniline group containing polymers of/Vs include: poly-TPD, TFB, P9, P11, P13, P15.

In some embodiments, the hole transport material has a mobility greater than 1 × 10^-4cm²Copolymers containing fluorene and aniline groups of/Vs include: TFB, P13, P15.

In the optoelectronic device provided in the tenth to thirteenth aspects of the present application, the quantum dot material of the core-shell structure further includes a core, and an intermediate shell layer located between the core and the outer shell layer; wherein the top energy level of the valence band of the core material is shallower than that of the shell material; the top energy level of the valence band of the intermediate shell layer material is between the top energy level of the valence band of the inner core material and the top energy level of the valence band of the outer shell layer material.

In some embodiments, the core material is selected from: at least one of the group II-IV, group II-VI, group II-V, group III-VI, group IV-VI, group I-III-VI, group II-IV-VI and group II-IV-V semiconductor compounds of the periodic table. In some embodiments, the core material is selected from: at least one of CdSe, CdZnSe, CdSeS, CdZnSeS, InP, InGaP, GaP, ZnTe and ZnTeSe. The core materials have good luminescence performance and have good matching effect with the outer shell layer of ZnSe, ZnS, CdZnS or ZnSeS.

In some embodiments, the intermediate shell material is selected from the group consisting of: at least one of CdZnSe, ZnSe, CdZnS, CdZnSeS, CdS, and CdSeS. The collocation principle of the intermediate shell layer in the embodiment of the application is as follows: the intermediate shell layer preferably forms continuous natural transition from the inner core to the outer layer in composition, so that the minimum lattice mismatch and the minimum lattice defect among the inner core, the intermediate shell layer and the outer shell layer are facilitated, and the optimal luminescence performance of the core-shell quantum dot material is realized; the intermediate shell layer generally needs to form a step-shaped energy level transition from the inner core to the outer shell layer, so that the effective injection of carriers, the effective constraint and the reduction of the scintillation of a crystal lattice interface are realized.

The tenth to thirteenth aspects of the present application provide an optoelectronic device, which may further incorporate optimization of a hole injection function layer in the optoelectronic device of the second or third aspects, and may include a first hole injection layer, where an absolute value of a difference between a work function of a first hole injection material of the first hole injection layer and a top valence band energy level of a hole transport material is less than or equal to 0.2 eV. Or the difference between the top energy level of the valence band of the material of the hole transport layer and the work function of the second hole injection material in the second hole injection layer is less than-0.2 eV. The hole utilization rate in the device is further improved, the hole injection rate is finely regulated, the injection of carriers in the device is balanced, and the recombination efficiency is improved; meanwhile, the influence of interface layer charge accumulation on the service life of the device is reduced.

The tenth to thirteenth aspects of the present application provide the optoelectronic device, further comprising an electron transport layer, wherein the electron transport layer comprises at least two sub-electron transport layers stacked together; wherein, the material of at least one layer of the electron transport layer is a metal oxygen group compound transport material. Or the material of at least one sub-electron transport layer is an organic transport material. Or, the material at least comprising one sub electron transport layer is a metal oxygen group compound transport material and the material of one sub electron transport layer is an organic transport material.

In the above embodiments of the present application, the device is not limited by the device structure, and may be a device of a positive type structure or a device of an inverted type structure.

In one embodiment, a positive-structure photovoltaic device includes a stacked structure of an anode and a cathode disposed opposite each other, a light-emitting layer disposed between the anode and the cathode, and the anode is disposed on a substrate. Further, a hole functional layer such as a hole injection layer, a hole transport layer and the like can be arranged between the anode and the light-emitting layer; an electron-functional layer such as an electron-transporting layer or an electron-injecting layer may be provided between the cathode and the light-emitting layer, as shown in fig. 14. In some embodiments of the positive-structure device, the optoelectronic device comprises a substrate, an anode disposed on a surface of the substrate, a hole transport layer disposed on a surface of the anode, a light-emitting layer disposed on a surface of the hole transport layer, an electron transport layer disposed on a surface of the light-emitting layer, and a cathode disposed on a surface of the electron transport layer.

In one embodiment, an inverse architecture photovoltaic device includes a stacked structure of oppositely disposed anodes and cathodes with a light emitting layer disposed between the anodes and cathodes with the cathode disposed on a substrate. Further, a hole functional layer such as a hole injection layer, a hole transport layer and the like can be arranged between the anode and the light-emitting layer; an electron-functional layer such as an electron-transporting layer or an electron-injecting layer may be provided between the cathode and the light-emitting layer, as shown in FIG. 15. In some embodiments of the device having an inverted structure, the optoelectronic device includes a substrate, a cathode disposed on a surface of the substrate, an electron transport layer disposed on a surface of the cathode, a light emitting layer disposed on a surface of the electron transport layer, a hole transport layer disposed on a surface of the light emitting layer, and an anode disposed on a surface of the hole transport layer.

In some embodiments, the substrate is not limited to be used, and a rigid substrate or a flexible substrate may be used. In some embodiments, the rigid substrate includes, but is not limited to, one or more of glass, metal foil. In some embodiments, the flexible substrate includes, but is not limited to, one or more of polyethylene terephthalate (PET), polyethylene terephthalate (PEN), Polyetheretherketone (PEEK), Polystyrene (PS), Polyethersulfone (PES), Polycarbonate (PC), Polyarylate (PAT), Polyarylate (PAR), Polyimide (PI), polyvinyl chloride (PV), Polyethylene (PE), polyvinylpyrrolidone (PVP), textile fibers.

In some embodiments, the anode material is selected without limitation and may be selected from doped metal oxides including, but not limited to, one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), magnesium-doped zinc oxide (MZO), and aluminum-doped magnesium oxide (AMO). Or a composite electrode with metal sandwiched between doped or undoped transparent metal oxides, including but not limited to AZO/Ag/AZO, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, ZnO/Ag/ZnO, ZnO/Al/ZnO, TiO₂/Ag/TiO₂、TiO₂/Al/TiO₂、ZnS/Ag/ZnS、ZnS/Al/ZnS、TiO₂/Ag/TiO₂、TiO₂/Al/TiO₂One or more of (a).

In some embodiments, the cathode material may be one or more of various conductive carbon materials, conductive metal oxide materials, metal materials. In some embodiments, the conductive carbon material includes, but is not limited to, doped or undoped carbon nanotubes, doped or undoped graphene oxide, C60, graphite, carbon fibers, porous carbon, or mixtures thereof. In some embodiments, the conductive metal oxide material includes, but is not limited to, ITO, FTO, ATO, AZO, or mixtures thereof. In some embodiments, the metallic material includes, but is not limited to, Al, Ag, Cu, Mo, Au, or alloys thereof; wherein the metal material is in a form including but not limited to a compact film, a nanowire, a nanosphere, a nanorod, a nanocone, a hollow nanosphere, or a mixture thereof; preferably, the cathode is Ag or Al.

In some embodiments, the quantum dot light emitting layer has a thickness of 8 to 100 nm. In some embodiments, the hole transport layer has a thickness of 10 to 150 nm. In some embodiments, the electron transport layer has a thickness of 10 to 200 nm. In practical applications, the electron functional layer, the light emitting layer, and the hole functional layer in the device may be designed to have suitable thicknesses according to the characteristics of the device in the above embodiments.

The preparation of the photoelectric device of the embodiment of the application comprises the following steps:

s10, obtaining a substrate deposited with an anode;

s20, growing a hole injection layer on the surface of the anode;

s30, growing a hole transport layer on the surface of the hole injection layer;

s40, depositing a quantum dot light-emitting layer on the hole transport layer;

s50, finally, depositing an electron transmission layer on the quantum dot light emitting layer, and evaporating a cathode on the electron transmission layer to obtain the photoelectric device.

Specifically, in step S10, the ITO substrate needs to undergo a pretreatment process, which includes the steps of: and cleaning the ITO conductive glass with a cleaning agent to primarily remove stains on the surface, then sequentially and respectively ultrasonically cleaning the ITO conductive glass in deionized water, acetone, absolute ethyl alcohol and deionized water for 20min to remove impurities on the surface, and finally drying the ITO conductive glass with high-purity nitrogen to obtain the ITO anode.

Specifically, in step S20, the step of growing the hole injection layer includes: preparing materials such as metal oxide into a thin film in a QLED device in a solution method mode, a vacuum sputtering mode and a vacuum evaporation mode; the solution method includes inkjet printing, spin coating, spray printing (spray printing), slot-die printing (slot-die printing), screen printing (screen printing), and the like.

Specifically, in step S30, the step of growing the hole transport layer includes: placing the ITO substrate on a spin coating instrument, and spin coating a prepared solution of the hole transport material to form a film; the film thickness is controlled by adjusting the concentration of the solution, the spin-coating speed and the spin-coating time, and then a thermal annealing process is performed at an appropriate temperature.

Specifically, in step S40, the step of depositing the quantum dot light-emitting layer on the hole transport layer includes: and (3) placing the substrate on which the hole transport layer is coated on a spin coater, spin-coating the prepared luminescent substance solution with a certain concentration to form a film, controlling the thickness of the luminescent layer to be about 20-60 nm by adjusting the concentration of the solution, the spin-coating speed and the spin-coating time, and drying at a proper temperature.

Specifically, in step S50, the step of depositing the electron transport layer on the quantum dot light emitting layer includes: the method comprises the steps of placing a substrate which is coated with a quantum dot light emitting layer in a spin coating instrument, carrying out spin coating film formation on a prepared electronic transmission composite material solution with a certain concentration through processes of dropping coating, spin coating, soaking, coating, printing, evaporation and the like, controlling the thickness of an electronic transmission layer to be about 20-60 nm by adjusting the concentration of the solution, the spin coating speed (preferably, the rotating speed is 3000-5000 rpm) and the spin coating time, and then annealing the film to form a film at the temperature of 150-200 ℃, and fully removing a solvent.

Specifically, in step S60, the step of preparing the cathode includes: and (3) placing the substrate on which the functional layers are deposited in an evaporation bin, and thermally evaporating a layer of 60-100nm metal silver or aluminum as a cathode through a mask plate.

In some embodiments, a method of fabricating an optoelectronic device further comprises encapsulating the stacked fabricated optoelectronic device; the curing resin adopted for packaging is acrylic resin, acrylic resin or epoxy resin; the resin curing employs UV irradiation, heating, or a combination of both. The packaging process can be carried out by a common machine or manually. Preferably, the oxygen content and the water content are both lower than 0.1ppm in the packaging treatment environment to ensure the stability of the device.

In some embodiments, the method for manufacturing an optoelectronic device further comprises introducing one or more processes including ultraviolet irradiation, heating, positive and negative pressure, an external electric field, and an external magnetic field after the optoelectronic device is packaged; the atmosphere in the application process may be air or an inert atmosphere.

In order to clearly understand the details of the above-described implementation and operation of the present application by those skilled in the art and to significantly embody the advanced performance of the optoelectronic devices of the embodiments of the present application, the above-described technical solution is illustrated by the following embodiments.

The device of the embodiment of the application adopts an ITO/HIL/HTL/QD/ETL/AL structure, certain heating treatment is carried out after packaging, and the advantages of the technical scheme of the application are explained in detail through matching and comparison of different functional layers in the device. In the following examples, the lifetime test was carried out by a constant current method at a constant 50mA/cm²Under the drive of current, a silicon optical system is adopted to test the brightness change of the device, the time LT95 of the brightness of the device from the highest point to the highest brightness of 95% is recorded, and then the service life of the device 1000nit LT95S is extrapolated through an empirical formula. The method is convenient for comparing the service lives of devices with different brightness levels, and has wide application in practical photoelectric devices.

1000nit LT95＝(L_Max/1000)^1.7×LT95

The energy level test method of each material in the embodiment of the application comprises the following steps: after the materials of all the functional layers are subjected to spin coating to form films, an energy level test is carried out by adopting a UPS (ultraviolet light electron spectroscopy) method.

Work function phi ═ h v-E_cutoffWhere hv is the energy of the incident excitation photon, E_cutoffFor excited secondary electron cut-offPlacing;

valence band top vb (homo): e_HOMO＝E^F-HOMO+ Φ, wherein E^F-HOMOThe difference value between the HOMO (VB) level and the Fermi level of the material corresponds to the initial edge of a first peak appearing at a low binding energy end in a binding energy spectrum;

bottom of conduction band (LOMO): e_LOMO＝E_HOMO-E^HOMO-LOMOWherein E is^HOMO-LOMOIs the band gap of the material and is obtained by UV-Vis (ultraviolet absorption spectrum).

Examples 1 to 7

In order to verify the influence of the hole injection barrier between the shell layer material of the quantum dot material and the hole transport material on the device performance, embodiments 1 to 7 are provided in the application, and the influence of the hole injection barrier on the device performance such as service life is explained by matching and comparing different HTLs and QDs.

Two kinds of quantum dots adopted in embodiments 1 to 7 of the present application are: blue QD1 with a shell of CdZnS (the core is CdZnSe, the intermediate shell is ZnSe, the thickness of the shell is 1.5nm, and the top level of the valence band is-6.2 eV), and blue QD2 with a shell of ZnS (the core is CdZnSe, the intermediate shell is ZnSe, the thickness of the ZnS shell is 0.3nm, and the top level of the valence band is 6.5 eV). The blue QD3 (core is CdZnSe, middle shell is ZnSe) with shell of ZnSeS is P9 (E) respectively_HOMO:5.1eV)、P15(E_HOMO5.8eV), and PEDOT PSS (E) is used as the hole injection layer_HOMO5.1eV), ZnO is adopted as the electron transmission layer, and the following table 1 is specifically shown:

TABLE 1

From the above table 1 and the test results in fig. 16 (time on abscissa and brightness on ordinate), it can be seen that for the same CdZnS (6.2eV) shell quantum dot, the HTL was changed from P15(5.8eV) to P9(5.1eV), Δ E_EML-HTLThe barrier difference is increased from 0.4eV to 1.1eV, the device lifetime is improved, and the 1000nit LT95S lifetime is improved from 0.72 to 1.26. In addition, for the same P15(5.8eV) material, quantum dot shells were changed from CdZnS (6.2eV) to ZnS (6.5eV), Δ E_EML-HTLThe barrier difference is increased from 0.4eV to 0.7eV, the device lifetime is remarkably improved, and the 1000nit LT95S lifetime is improved from 0.72 to 6.29.

It can be seen that the top energy level difference Δ E of the valence band can be adjusted for either HTL or EML materials_EML-HTLThe injection balance of the device is optimized and the service life of the device can be enhanced when the injection balance is increased to more than 0.5 eV. The injection efficiency of the holes is reduced by improving the hole injection barrier, the injection balance of the holes and electrons in the light-emitting layer can be better balanced, and the light-emitting efficiency and the light-emitting service life of the device are improved.

Examples 8 to 11

Further, in order to verify the influence of the interface energy level barrier from the HIL to the HTL on the device performance, embodiments 8 to 11 are provided in the application, and the delta E is illustrated by matching and comparing different HTLs and HTLs_HTL-HILThe effect of the hole injection barrier on the device lifetime and other properties.

In embodiments 8 to 9 of the present application, blue quantum dots with ZnS as shells (CdZnSe as a core, ZnSe as an intermediate shell, ZnSe as a shell thickness of 0.3nm, and a valence band top level of 6.5eV) are used, in embodiments 10 to 11, red quantum dots with ZnS as shells (CdZnSe as a core, ZnSe as an intermediate shell, ZnSe as a shell thickness of 0.3nm, and a valence band top level of 6.5eV) are used, and hole transport materials are respectively P9 (E9) (E_HOMO:5.5eV)、P11(E_HOMO:5.5eV)、P13(E_HOMO4.9eV), and PEDOT PSS (E) is used as the hole injection layer_HOMO5.1eV) and HIL2 (work function: 5.6eV), ZnO was used for the electron transport layer, as shown in table 2 below:

TABLE 2

And (3) annotation: when Δ E_HTL-HILDelta E at < 0.2eV with existing HIL materials and experimental data_EML-HTLNecessarily greater than 0.5 eV.

As can be seen from the above table 2 and the test results of fig. 17 and 18 (time on the abscissa and brightness on the ordinate), the blue quantum dot devices of examples 8 and 9 are relatively high, and the red quantum dot devices of examples 10 and 11 are relatively high, when HTL is usedHole injection energy barrier Δ E to HIL_HTL-HIL< -0.2eV, relative to Δ E_HTL-HILIn the examples having-0.2 eV or more, the device lifetime of 1000nit LT95S was further improved. The hole injection barrier from the anode to the HIL is increased, the integral rate of hole injection in the QLED device is reduced, the number of holes entering the QLED device is effectively controlled, and the carrier recombination efficiency is improved; and the charge accumulation formed at the interface of the HTL and the HIL by excessive hole injection is reduced, and the light-emitting life of the device is prolonged.

Examples 12 to 19

Further, in order to verify the influence of the interface energy level barrier from the HIL to the HTL on the device performance, examples 12 to 19 are provided in the present application, and the | Δ E is illustrated by matching and comparing different HTLs and HTLs_HTL-HILThe influence of the | hole injection barrier on the performance of the device such as the driving voltage.

In embodiments 12 to 14 of the present application, blue quantum dots with ZnS as shells (CdZnSe as a core, ZnSe as an intermediate shell, ZnSe as a shell thickness of 0.3nm, and a valence band top level of 6.5eV) are used, in embodiments 15 to 19, red quantum dots with ZnS as shells (CdZnSe as a core, ZnSe as an intermediate shell, ZnSe as a shell thickness of 0.3nm, and a valence band top level of 6.5eV) are used, and hole transport materials are respectively P9 (E9) (E_HOMO:5.5eV)、P13(E_HOMO:4.9eV)、TFB(E_HOMO5.4eV), and PEDOT PSS (E) is adopted as the hole injection layer_HOMO5.1eV), HIL1-1 (work function: 5.4eV) and HIL1-2 (work function: 5.3eV), and ZnO was used for the electron transport layer, as shown in Table 3 below:

TABLE 3

As can be seen from the above Table 3 and the test results of FIGS. 19 and 20 (time on the abscissa and voltage on the ordinate), the barrier | Δ E of the hole injection level between the HTL and the HIL_HTL-HILI is small0.2eV or less with respect to | Δ E_HTL-HILIn the embodiment with the | larger than 0.2, the charge accumulation on the hole transmission side of the device is small, the driving voltage amplitude of the device is obviously reduced under the long-time constant current operation of the device, and the service life of the device is improved by 1000nit LT 95S. Meanwhile, when the potential barrier difference between the HIL and the HTL is small, the interface almost has no charge accumulation, the opposite side has no aging, the hole injection capability of the device is stable, and the service life of the device is also prolonged. The reduction of the hole injection energy level barrier is beneficial to the effective injection of holes from the HIL to the HTL, the elimination of the barrier and interface charges and the reduction of the integral resistance of the device, thereby prolonging the service life of the device.

Examples 20 to 25

Further, in order to verify the influence of the hole transport layer material on the device performance, embodiments 20 to 25 are provided in the present application, and the matching and comparison of different HTL materials is used to demonstrate the influence of the HTL material on the establishment of a hole injection barrier, optimization of the carrier recombination efficiency, the device lifetime, and other properties.

In embodiments 20 to 25 of the present application, blue quantum dots with ZnS as shells (CdZnSe as a core, ZnSe as an intermediate shell, 0.3nm in shell thickness, and 6.5eV in valence band top level) are used, and hole transport materials are respectively P12 (E)_HOMO:5.8eV)、P13(E_HOMO:4.9eV)、TFB(E_HOMO5.4eV), and PEDOT PSS (E) is used as the hole injection layer_HOMO5.1eV), as shown in Table 4 below:

TABLE 4

As can be seen from the results of the above Table 4 and the test of FIG. 21 (abscissa is time, ordinate is brightness), the hole transport layer can be made of a mixture of materials with different energy levels, and Δ E can be flexibly controlled_EML-HTLInjection barrier of delta E_EML-HTLThe energy barrier of 0.5eV or more, and the lowering of QThe hole injection rate in the LED device can regulate and control the injection and recombination efficiency of carriers, and meanwhile, the irreversible damage of the HIL and HTL interface charge accumulation to the service life performance of the device can be reduced. And, the test result shows that the device of the mixed hole transport layer has better luminous life. The HTL of the deep energy level may reduce a luminance variation in a lifetime test caused by exciton transfer of the HTL and the QD, and reduce a rising section. Therefore, through the mixing of the shallow energy level and the deep energy level, the service life of the device can be ensured, and meanwhile, the rising section of the brightness of the device is reduced, so that the device can rapidly enter a stable state, and the subsequent test and application are facilitated. As can be seen by comparing examples 22, 24 and 25 with the attached FIG. 21, from examples 22 to 24 to 25, the doping ratio of the material of the deep energy level is increased, the service lives are all between 60 h and 80h, the service life difference is small, and the brightness rise time in the test is respectively about 7h, 5h and 4 h; in examples 22, 24, and 25, compared with example 21, the proportion of the deep energy level material is higher, the regulation range of the mobility of the hole transport material is larger, and quantum dot devices with longer service life are easier to obtain.

Examples 26 to 28

Further, in examples 26 to 28, when the outer shell layer of the blue quantum dot material was ZnS (the core was CdZnSe, the intermediate shell layer was ZnSe, and the thickness of the outer shell layer was 0.2 to 2.0nm), appropriate Δ E was constructed_EML-HTLThe absolute value of the top valence band energy level of the hole transport material is not more than 6.0eV, as shown in examples 26-28 in Table 5 below (PEDOT: PSS (E) is used for the hole injection layer)_HOMO5.1eV), and the electron transport layer adopts ZnO):

TABLE 5

From the above table 5 and the test results shown in fig. 22 (the abscissa is time, and the ordinate is brightness), it can be seen that when the shell layer of the quantum dot light emitting layer material is ZnS, and the thickness of the shell layer is 0.2-2.0nm, the valence band top energy level difference (Δ E) between the preferred hole transport layer material and the quantum dot shell layer material in the quantum dot light emitting layer is preferably selected_EML-HTL) The range is 1.0-1.6eV, and the device has better radiation effectLight lifetime.

Examples 29 to 31

Further, in examples 29 to 31, when the outer shell of the blue quantum dot material was ZnSe (CdZnSe as the core, ZnSe as the intermediate shell, and 2 to 5nm thick outer shell), a suitable Δ E was constructed_EML-HTLThe absolute value of the energy level barrier and the top valence band energy level of the hole transport material should be 5.4eV or less, as shown in examples 29 to 31 in Table 6 (the hole injection layer is PEDOT: PSS (E)_HOMO5.1eV), ZnO is adopted as the electron transport layer):

TABLE 6

As can be seen from the test results of table 6 and fig. 23 (the abscissa is time, and the ordinate is brightness), when the shell layer of the quantum dot light emitting layer material is ZnS and the shell layer thickness is 2 to 5nm, the valence band top energy level difference (Δ E) between the preferred hole transport layer material and the quantum dot shell layer material in the quantum dot light emitting layer is obtained_EML-HTL) The range is 0.5-1.0 eV, and the device has better luminous life.

Examples 32 to 35

Further, in examples 32 to 35, when the outer shell of the blue quantum dot material is CdZnS (the core is CdZnSe, the middle shell is ZnSe, and the thickness of the outer shell is 0.5 to 3.0nm), a suitable Δ E is constructed_EML-HTLThe absolute value of the top valence band energy level of the hole transport material is not more than 5.9eV, as shown in Table 7 and examples 32 to 35 (the hole injection layer is PEDOT: PSS (E)_HOMO5.1eV), ZnO is adopted as the electron transport layer):

TABLE 7

As can be seen from the above Table 7 and the test results shown in FIG. 24 (time on the abscissa and brightness on the ordinate), when the outer shell of the luminescent layer material is CdZnS and the thickness of the outer shell is 0.5-3.0nm, the preferable thickness isValence band top energy level difference (delta E) between hole transport layer material and quantum dot shell layer material in quantum dot light emitting layer_EML-HTL) The range is 0.8-1.4eV, and the device has better luminous life.

Examples 36 to 38

Further, in examples 36 to 38, when the outer shell layer of the blue quantum dot material was ZnSeS (CdZnSe as the core, ZnSe as the intermediate shell layer, and 1.0 to 4.0nm in thickness of the outer shell layer), a suitable Δ E was constructed_EML-HTLThe absolute value of the energy level barrier and the top valence band energy level of the hole transport material should be 5.7eV or less, as shown in the following Table 8, examples 36 to 38 (the hole injection layer is PEDOT: PSS (E)_HOMO5.1eV), ZnO is adopted as the electron transport layer):

TABLE 8

As can be seen from the test results in table 8 and fig. 24 (the abscissa is time, and the ordinate is brightness), when the cladding layer of the quantum dot light emitting layer material is CdZnS and the thickness of the cladding layer is 0.5-3.0nm, the valence band top energy level difference (Δ E) between the preferred hole transport layer material and the quantum dot cladding layer material in the quantum dot light emitting layer is preferably obtained_EML-HTL) The range is 0.9-1.4eV, and the device has better luminous life.

Examples 39 to 43

Further, in order to verify the effect of the hole injection layer on the device performance, the present application provides the following examples. In examples 39 to 41, red quantum dots having a ZnS shell (CdZnSe as a core, ZnSe as an intermediate shell, and 6.5eV for a top valence band) were used. In examples 42 to 43, red quantum dots (CdZnSe as the core, ZnSe as the intermediate shell, and 6.5eV as the valence band top level) with ZnS as the shell were used, and ZnO was used as the electron transport layer. As shown in table 9:

TABLE 9

From the above-mentioned watch9 and fig. 26 and 28 (abscissa is time, ordinate is voltage), and 27 and 29 (abscissa is time, ordinate is luminance), it can be seen that, after the HIL layer is removed from the device, the charge accumulation between the hole injection layer and the hole transport layer and the influence of acidic PEDOT on the device disappear, and under the long-time constant current operation of the device, the driving voltage of the device hardly changes, and even because the charge fills up the defect in the device, the driving voltage of the device has a tendency to decrease. After the HIL-free device is prepared by adopting the P11 material with higher mobility, the driving voltage of the device is reduced more obviously under the long-time constant current operation of the device, which shows that the preferred HTL mobility is higher than 1x10^-3cm²and/Vs, the device voltage rise can be better inhibited.

In addition, when inorganic metal oxide MoO is used₃PSS as hole injection layer material instead of organic PEDOT due to MoO₃The damage of the hole injection material is effectively inhibited, so that the voltage rise of the device in the working engineering is obviously reduced compared with that of an organic hole injection layer material device, and the actual measurement duration of the service life of the device is effectively prolonged.

The above description is only a preferred embodiment of the present application and should not be taken as limiting the present application, and any modifications, equivalents, improvements, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (10)

1. An optoelectronic device, comprising: the quantum dot light-emitting diode comprises an anode, a hole transport layer on the anode, a quantum dot light-emitting layer on the hole transport layer and a cathode on the quantum dot light-emitting layer, wherein the quantum dot light-emitting layer comprises a quantum dot material with a core-shell structure, the outer shell layer of the quantum dot material is ZnSeS, and the mobility of the hole transport material in the hole transport layer is higher than 1x10^-4cm²/Vs。

2. The optoelectronic device according to claim 1, wherein in the quantum dot material, the ZnSeS shell layer has a thickness of 1.0 to 4.0 nm;

and/or the wavelength of the luminescence peak of the quantum dot material is 400-700 nm.

3. The optoelectronic device according to claim 1 or 2, wherein the difference in valence band top energy levels of the ZnSeS material and the hole transport material is 0.5eV or more.

4. The optoelectronic device according to claim 3, wherein the difference in valence band top energy levels of the ZnSeS material and the hole transporting material is 0.9-1.4 eV;

and/or the absolute value of the top valence band energy level of the hole transport material is 4.9-5.7 eV.

5. The optoelectronic device according to claim 1,2 or 4, wherein the hole transport material is selected from the group consisting of: at least one of polymer containing aniline group and copolymer containing fluorene group and aniline group.

6. The optoelectronic device according to claim 5, wherein the polymer comprising aniline groups comprises: poly-TPD, TFB, P9, P11, P13, P15;

and/or the copolymer containing fluorene groups and aniline groups comprises: TFB, P13, P15;

and/or the mobility of the hole transport material is higher than 1x10^-3cm²The absolute value of the valence band top energy level of the hole transport material is 4.9-5.4 eV.

7. The optoelectronic device of claim 1,2,4, or 6, wherein the quantum dot material of the core-shell structure further comprises an inner core, and an intermediate shell layer located between the inner core and the outer shell layer; wherein the content of the first and second substances,

the top energy level of the valence band of the inner core material is shallower than that of the outer shell material;

the top energy level of the valence band of the intermediate shell layer material is between the top energy level of the valence band of the inner core material and the top energy level of the valence band of the outer shell layer material.

8. The optoelectronic device according to claim 7, wherein the core material is selected from the group consisting of: at least one of group II-IV, group II-VI, group II-V, group III-VI, group IV-VI, group I-III-VI, group II-IV-VI and group II-IV-V semiconductor compounds of the periodic table of elements;

and/or, the core material is selected from: at least one of CdSe, CdZnSe, CdSeS, CdZnSeS, InP, InGaP, GaP, ZnTe and ZnTeSe;

and/or, the intermediate shell material is selected from: at least one of CdZnSe, ZnSe, CdZnS, CdZnSeS, CdS, and CdSeS.

9. The optoelectronic device according to claim 8, wherein the light-emitting device further comprises a first hole injection layer, and an absolute value of a difference between a work function of the first hole injection material of the first hole injection layer and a top valence band energy level of the hole transport material is 0.2eV or less;

or the light-emitting device further comprises a second hole injection layer, and the difference between the top energy level of the valence band of the material of the hole transport layer and the work function of a second hole injection material in the second hole injection layer is less than-0.2 eV.

10. The optoelectronic device according to claim 9, wherein the optoelectronic device further comprises an electron transport layer comprising at least two sub-electron transport layers arranged in a stack;

wherein, the material of at least one layer of the electron transport layer is a metal oxygen group compound transport material; and/or the material of at least one sub-electron transport layer is an organic transport material.

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