CN116471903A - Non-fullerene organic solar cell based on non-halogenated mixed solvent and preparation method thereof - Google Patents

Abstract

The invention discloses a non-fullerene organic solar cell based on a non-halogenated mixed solvent and a preparation method thereof, wherein carbon disulfide (CS) ₂ ) Preparing polymer donor/non-fullerene small molecule acceptor blend solution by mixing para-xylene (PX) with non-halogenated solvent, regulating solvent proportion to obtain optimal solvent formula, preparing high-quality organic active layer blend film by spin coating method in main solvent CS ₂ Introducing a solvent PX with a high boiling point and lower solubility to an organic polymer donor, respectively regulating and controlling ordered aggregation of the organic polymer donor and a non-fullerene small molecular acceptor in the solution neutralization film forming process, and then assisting in post-treatment regulation and control of an active layer film to realize the non-halogenated solvent processing of the organic solar cell photoelectric conversionThe improvement of the conversion efficiency, and further the promotion of the non-halogenated solvent processing of the organic solar cell is towards industrial production and commercial application.

Description

Non-fullerene organic solar cell based on non-halogenated mixed solvent and preparation method thereof

Technical Field

The invention belongs to the technical field of solar cells, and particularly relates to a non-fullerene organic solar cell based on a non-halogenated mixed solvent and a preparation method thereof.

Background

Organic solar cells using an organic or polymeric semiconductor material as an electron donor and an electron acceptor and further blending the donor and the acceptor as a photovoltaic active layer have been attracting attention in recent years due to their low cost solution processing, flexibility, light weight, and the like. Green preparation of high-performance organic solar cells is a necessary requirement for industrial preparation of organic solar cells, however, as the solubility of photovoltaic materials in common non-halogenated solvents is low, the corresponding active layer film microstructure is poor, so that the photovoltaic performance of the organic solar cells prepared by the green solvents is low, and particularly the non-fullerene organic solar cells with high performance at present, the processing and preparation of high-efficiency cell devices by the non-halogenated solvents are still an important challenge.

There have been studies on how to control the microstructure of non-fullerene organic photovoltaic thin films processed with non-halogenated solvents to improve the photoelectric conversion efficiency of the battery. Comprising increasing the solubility of a donor or acceptor material in a non-halogenated solvent by heating an active layer solution or substrate, inhibiting the formation of large-sized aggregates to the acceptor, and improving the cell efficiency. However, there is still a problem in the solution heating preparation that the dissolution or aggregation state of the material, and the film forming kinetics process are extremely sensitive to the solution or substrate temperature, so that the efficiency of the battery device is batch-like and is difficult to stably repeat.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a non-fullerene organic solar cell based on a non-halogenated mixed solvent and a preparation method thereof, so as to solve the problem of batch repeatability in green preparation of the organic solar cell with high photoelectric conversion efficiency in the prior art.

In order to achieve the purpose, the invention is realized by adopting the following technical scheme:

a preparation method of a non-fullerene organic solar cell based on a non-halogenated mixed solvent,

sequentially stacking and preparing an anode, a hole transport layer, a photoactive layer, an electron transport layer and a cathode;

the photoactive layer is prepared by coating a blending solution on the hole transport layer and annealing, wherein the solute of the blending solution is a mixture of an organic polymer donor D18 and a non-fullerene electron acceptor L8-BO, and the solvent is a mixed solution of carbon disulfide and p-xylene.

The invention further improves that:

preferably, the mass ratio of the organic polymer donor D18 and the non-fullerene electron acceptor L8-BO in the solute is 1 (1-2).

Preferably, the concentration of the blending solution is 5-20 mg mL ^–1 。

Preferably, the mixing volume ratio of the carbon disulfide and the paraxylene in the solvent is (90-100): 1-10.

Preferably, the blend solution is stirred for 1 to 3 hours at 30 to 50 ℃ after the solute and the solvent are mixed in the glove box.

Preferably, the blend solution is spin coated onto the hole transport layer at 600-3000rpm.

Preferably, the annealing temperature is 50-200 ℃ and the annealing time is 0-120min.

Preferably, the mixed solution is spin-coated on the hole transport layer at 1200 rpm;

the preparation process of the mixed solution comprises the following steps: the method comprises the steps of mixing a solute and a solvent in a glove box, wherein the solute is a mixture of an organic polymer donor D18 and a non-fullerene electron acceptor L8-BO in a mass ratio of 1:1.6, the solvent is a mixed solution of carbon disulfide and p-xylene in a volume ratio of 97:3, and the concentration of the mixed solution is 13mg mL ^–1 The method comprises the steps of carrying out a first treatment on the surface of the And (3) stirring the mixed solution at 50 ℃ for 1h, and then carrying out annealing treatment at 90 ℃ for 10min to obtain the mixed solution.

A non-fullerene organic solar cell based on a non-halogenated mixed solvent, comprising:

an anode that collects holes;

a cathode for collecting electrons;

a photoactive layer between the anode and the cathode, the photoactive layer being a blend of a polymeric donor D18 and a non-fullerene electron acceptor L8-BO; the photoactive layer is prepared by a blending solution, wherein the solute of the blending solution is a mixed solution of a macromolecule donor D18 and a non-fullerene electron acceptor L8-BO, and the solvent is carbon disulfide and paraxylene;

a hole transport layer interposed between the anode and the photoactive layer;

an electron transport layer interposed between the cathode and the photoactive layer.

Preferably, the thickness of the photoactive layer is between 50nm and 300nm.

Compared with the prior art, the invention has the following beneficial effects:

the invention discloses a preparation method for processing an efficient non-fullerene organic solar cell based on a non-halogenated mixed solvent, which uses carbon disulfide (CS) ₂ ) Preparing polymer donor/non-fullerene small molecule acceptor blend solution by mixing para-xylene (PX) with non-halogenated solvent, regulating solvent proportion to obtain optimal solvent formula, preparing high-quality organic active layer blend film by spin coating method in main solvent CS ₂ Wherein a solvent PX with a low solubility of high boiling point to an organic polymer donor is introduced, D18 is added in CF and CS ₂ And PX, D18 and L8-BO in CS, are very different in solubility in each of the three solvents ₂ The high solubility of (c) ensures excellent solution processability at room temperature, poor solubility of D18 in PX, and during spin coating, the first precipitated D18 forms fibers and then promotes moderate aggregation of L8-BO around D18, but avoids substantial aggregation. The method is used for respectively regulating and controlling the ordered aggregation of the organic polymer donor and the non-fullerene small molecular receptor in the solution and film forming process, and further assisting in the post-treatment regulation and control of the active layer film so as to realize the improvement of the photoelectric conversion efficiency of the non-halogenated solvent processing organic solar cell, and the method for repeatedly preparing the high-efficiency device based on the room temperature condition is expected to promote the commercialized application of the organic solar cell.

Further, the organic solar cell of the present invention utilizes a non-halogenated solvent CS in the preparation process ₂ The solvent has good solubility for the donor D18 and the acceptor L8-BO, and can dissolve photovoltaic material and enhance L8-BO at room temperatureThe solution was moderately aggregated. Pure CS ₂ Wherein D18 and L8-BO produce a uniform mixed film, L8-BO is in CS ₂ More planar conformations are adopted and stronger aggregation is shown, the effective pi-pi accumulation of L8-BO in the solid film is promoted, and the open-circuit voltage of the organic solar cell device reaches the ultra-high level of 0.936V.

Further, the size of the phase region is further controlled by adding a small amount of non-halogenated additive to PX, so that the precipitation of D18 before liquid-liquid (L-L) phase separation is effectively promoted, and the strong pi-pi stacking aggregation of L8-BO is partially reserved. An ideal film microstructure is formed, the uniformity of the whole film is good, the phase separation size is moderate, the number of acceptor interfaces is large, and the charge transmission and exciton dissociation are facilitated; the preparation method comprises the steps of forming a bicontinuous phase separation network with nano-scale domains and good pi-pi stacking, and treating the obtained optimal form by mixed non-halogenated solvent, wherein the charge carrier dynamics is obviously prolonged, and exciton dissociation and charge transmission are enhanced. Thus, a photoelectric conversion efficiency of 17.50% was obtained, compared with a single CS ₂ And 15.48% and 17.11% higher for the halogenated solvent CF treatment. The work provides a brand new strategy for solving the problem of high-efficiency preparation of the non-halogenated OSC, and accelerates the process of converting the non-halogenated OSC into industrialization.

The invention also discloses a non-fullerene organic solar cell prepared based on the non-halogenated mixed solvent strategy, and the cell device is prepared by a spin coating method and has excellent photoelectric conversion efficiency.

Drawings

FIG. 1 is a graph comparing current density versus voltage curves of organic solar cells prepared by the method described in the examples of the present invention with a single non-halogenated solvent, halogenated solvent.

FIG. 2 is a graph comparing the external quantum efficiency curves of organic solar cells prepared by the method according to the embodiment of the invention with those prepared by a single non-halogenated solvent.

Fig. 3 is a graph comparing the photo-generated current density versus effective voltage curves of organic solar cell devices prepared by the method described in the examples of the present invention with a single non-halogenated solvent, halogenated solvent.

FIG. 4 is a graph comparing the method described in the examples of the present invention with a single non-halogenated solvent, active layer blend film scanning probe microscope (AFM) prepared from halogenated solvents. Wherein, (a) is a phase diagram of the active layer blend film prepared by the method and a single non-halogenated solvent, halogenated solvent in the embodiment of the invention; (b) The figures are height views of the active layer blend films prepared by the method described in the examples of the present invention with a single non-halogenated solvent, halogenated solvent.

FIG. 5 is a field emission ultra-high resolution Transmission Electron Microscope (TEM) contrast of a film blend of an active layer prepared by the method described in the examples of the invention with a single non-halogenated solvent, halogenated solvent.

FIG. 6 is a chemical structure of D18 and L8-BO used in the examples of the present invention.

FIG. 7 is a bar graph of the solubility of D18 and L8-BO in three pure solvents used in the examples of the invention.

Fig. 8 is a schematic view of the internal microstructure of the photovoltaic active layer.

Detailed Description

The invention is described in further detail below with reference to the attached drawing figures and to specific examples:

the invention discloses a high-efficiency non-fullerene organic solar cell processed based on a non-halogenated mixed solvent and a preparation method thereof, wherein carbon disulfide (CS) ₂ ) Preparing polymer donor/non-fullerene small molecule acceptor blend solution by mixing para-xylene (PX) with non-halogenated solvent, regulating solvent proportion to obtain optimal solvent formula, preparing high-quality organic active layer blend film by spin coating method in main solvent CS ₂ The organic solar cell is characterized in that a solvent PX with a high boiling point and lower solubility to an organic polymer donor is introduced, the ordered aggregation of the organic polymer donor and a non-fullerene small molecule acceptor in a solution and film forming process is regulated and controlled respectively, and then the regulation and control of an active layer film microstructure are assisted, so that the improvement of the photoelectric conversion efficiency of the non-halogenated solvent processing organic solar cell is realized, and the non-halogenated solvent processing organic solar cell is further promoted to be applied to industrial production and commercialization.

One of the embodiments of the present invention discloses a method for preparing a high-efficiency non-fullerene organic solar cell by non-halogenated mixed solvent, comprising the following steps,

step 1, cleaning an ITO glass substrate: ultrasonic cleaning is carried out for 30min by ultrapure water, acetone and isopropanol respectively in sequence, then drying is carried out for 30min at 120 ℃ in a forced air drying oven, and the substrate is dried.

Step 2, spin-coating a hole transport layer;

firstly, ultraviolet ozone treatment is carried out for 25min;

thereafter, an aqueous solution of PEDOT: PSS was spin-coated on the ITO glass substrate. Preferably, an aqueous solution of PEDOT: PSS filtered through an aqueous 0.45 μm filter was spin-coated on an ITO glass substrate at 5000rpm for 40s (thickness about 40 nm) and baked at 150℃for 20min.

Step 3, carbon disulphide (CS) ₂ ) Preparing a photoactive layer solution by using a binary mixed solvent of Paraxylene (PX);

firstly, weighing an organic polymer donor D18 and a non-fullerene small molecular acceptor L8-BO (substances shown in fig. 6) in air as solutes, wherein the mass ratio of the organic polymer donor D18 to the non-fullerene small molecular acceptor L8-BO is 1 (1-2), preferably, the mass ratio is 1:1.6, and the prepared organic solar cell device has high and balanced short-circuit current density and filling factor under the acceptor feeding ratio; the solute was placed in a glove box.

Then CS with the volume ratio of (90-100) to (1-10) is added into the glove box ₂ And PX binary mixed solvent, the concentration is 5-20 mg mL ^–1 Is preferably at a concentration of 13mg mL ^–1 The device film prepared at this concentration has a moderate thickness, which is advantageous for light absorption without decreasing its fill factor. CS in solvent ₂ And PX add up to 100%, preferably CS in solvent ₂ The volume ratio is 97% and the volume ratio of PX is 3%, at which ratio the highest short circuit current density and fill factor can be obtained without high open circuit voltage loss. The mixed solution is stirred at 30-50 ℃ for 1-3 hours, preferably at 50 ℃ for 1 hour, ensuring that the donor is sufficiently dispersed in the solution.

The film microstructure formed by the film at this ratio consists of a bicontinuous phase separation network with nanoscale domains and good pi-pi stacking, this optimum morphology results in significantly prolonged charge carrier kinetics, efficient exciton dissociation and charge transport, the active layer film having dimensions of 1.5cm by 1.5cm and a thickness of between 50nm and 300nm, preferably 120nm, ensuring efficient light absorption, higher short-circuit current densities and fill factors.

Step 4, preparing a photoactive layer film;

the active layer blend solution is spin coated on the hole transport layer, the spin coating process is dynamic spin coating, and the spin speed of the spin coater is 600-3000rpm, preferably 1200rpm. And (3) annealing the spin-coated film at 50-200 ℃ for 0-120min, wherein the spin-coated film is preferably annealed at 90 ℃ for 10min, and the active layer has the optimal morphology under the annealing condition.

Step 5, spin coating an electron transport layer;

firstly, cooling the annealed active layer film to room temperature;

thereafter, a solution of N, N '-bis (N, N-dimethylpropane-1-amine oxide) perylene-3, 4,9, 10-tetracarboxylic diimine (PDINO) or poly [ (9, 9-bis (3' - (N, N-dimethylamino) propyl) fluorenyl-2, 7-diyl) -alt- [ (9, 9-di-N-octylfluorenyl 2, 7-diyl) -bromo (PFNBr) was spin cast onto the active layer;

preferably, the methanolic solution of PDINO is stirred overnight at room temperature, pdino=2 mg mL ^–1 Cast onto the active layer at 3000rpm to form a cathode interlayer (about 10 nm).

Step 6, evaporating a metal electrode;

first, all samples were transferred into a vacuum chamber.

Then, the metal aluminum or metal silver electrode is used for 2X 10 ^-4 Heat evaporating the pressure of Pa onto the sample; wherein the thickness of the electrode is 50-300nm, preferably 100nm.

Step 6, testing the photoelectric conversion efficiency of the organic solar cell;

wherein the photoelectric conversion efficiency of the organic solar cellAnd the parameters are in a standard sunlight (AM1.5G, 100mW cm) ^-2 ) Parameters such as open-circuit voltage, short-circuit current density, filling factor, photoelectric conversion efficiency and the like are obtained through the test, so that the photoelectric performance of the device is evaluated. The J-V test voltage ranges are as follows: the normal scanning is-0.4-1.2V, the scanning step is 0.01V, and the scanning delay time is 0.02s. The paper was tested using a 3A solar simulator manufactured by Sirius-SS150A (light instruments limited in beijing Zhuo Lihan) as the light source, and a digital source meter manufactured by Keithley2400 (giga-line company in usa).

Step 7, testing the external quantum efficiency of the organic solar cell;

the External Quantum Efficiency (EQE) is one of the main performance indexes of the photovoltaic device, and the value of the EQE is the ratio of the number of electron-hole pairs generated in unit time to the number of incident photons at a certain wavelength, and the parameter can reflect the photoelectric conversion capability of the solar cell. Under the irradiation of different wavelengths, an external quantum efficiency curve of the corresponding wavelength of the organic solar cell can be obtained, and the current of all the wavelengths is accumulated, so that the highest short-circuit current density of the cell device can be calculated, and the method can be used for checking the accuracy of the short-circuit current density obtained by the J-V curve. The paper uses QTest Station 2000ADI system (ex new energy science co., usa) for EQE testing at a wavelength range of 300-1000nm and uses silicon chips to subtract background.

Step 8, testing the exciton dissociation efficiency of the organic solar cell;

wherein the photocurrent density (J _ph ) And effective voltage (V) _eff ) To evaluate charge generation and collection efficiency in an actual device. The J-V test voltage ranges are as follows: the normal scan is-8-2V, the scanning step is 0.05V, and the scanning delay time is 0.02s. The paper was tested using a 3A solar simulator manufactured by Sirius-SS150A (light instruments limited in beijing Zhuo Lihan) as the light source, and a digital source meter manufactured by Keithley2400 (giga-line company in usa).

The non-halogenated mixed solvent prepared by the method is used for preparing a high-efficiency non-fullerene organic solar cell, and the high-efficiency non-fullerene organic solar cell comprises an anode (ITO glass substrate) for collecting holes, a hole transport layer, a macromolecule donor/non-fullerene electron acceptor photovoltaic active layer for generating hole-electron pairs, an electron transport layer and a cathode (metal electrode) for collecting electrons, wherein the anode is arranged from bottom to top.

The photovoltaic active layer prepared by the method is composed of D18 and L8-BO, the D18 and L8-BO form a bicontinuous phase separation network, donor and acceptor materials in a framework of the network are separated from each other, but are mutually communicated, namely, the donor network is communicated with the donor network, and the acceptor network is communicated with the acceptor network, so that a network structure with moderate phase separation size and more donor interfaces is formed, and the film morphology is favorable for charge transmission and exciton dissociation.

The invention provides a mixed non-halogenated solvent strategy for processing and preparing a high-efficiency organic solar cell, and the structure of the device sequentially comprises an ITO glass substrate, a hole transport layer, a photoactive layer, an electron transport layer and a metal electrode. In the present invention, the use of a conventional halogenated solvent CF, a single non-halogenated solvent CS, has been studied for organic solar cells based on organic polymer donors/non-fullerene small molecule acceptors ₂ And mixing the non-halogenated solvent to influence the micro structure of the active layer film of the organic solar cell, thereby further optimizing the photovoltaic performance of the organic solar cell processed by the non-halogenated solvent. The use of carbon disulphide, a non-halogenated solvent, has very good solubility for both the donor D18 and the acceptor L8-BO used, and it is capable of dissolving the photovoltaic material at room temperature and enhancing the solution aggregation of L8-BO. Pure CS ₂ The D18 and L8-BO in the organic solar cell device generate uniform mixed films, the open-circuit voltage of the organic solar cell device reaches the ultra-high level of 0.936V, pi-pi accumulation is enhanced, but the prepared active layer has overlarge phase separation size, so that the short-circuit current density and the filling factor are lower, and the photoelectric conversion efficiency of the device is not high. The phase zone size is further controlled by the addition of a small amount of non-halogenated additive para-xylene, which effectively promotes the deposition of D18 prior to liquid-liquid (L-L) phase separation, but primarily retains the pi-pi stacking aggregation of L8-BO. This forms an "ideal" thin film microstructure consisting of a bicontinuous phase-separated network with nanoscale domains and good pi-pi stacking, the best of mixed non-halogenated solventsThe preferred morphology results in significantly prolonged charge carrier kinetics, efficient exciton dissociation, and enhanced charge transport. Thus, a photoelectric conversion efficiency of 17.50% was obtained, compared with a single CS ₂ And 15.48% and 17.11% of the halogenated solvent CF treatment are higher, a brand new strategy is provided for solving the problem of high-efficiency preparation of the non-halogenated organic solar cell, and the process of converting the non-halogenated organic solar cell into industrialization is accelerated.

Example 1

The best embodiment of the method for preparing a high efficiency organic solar cell by mixing non-halogenated solvent strategy (using CS ₂ with PX is abbreviated as shown in FIGS. 1-5 and Table 1), comprising the following preparation steps:

first, the ITO glass substrate is cleaned: ultrasonic cleaning is carried out for 30min by ultrapure water, acetone and isopropanol respectively in sequence, then drying is carried out for 30min at 120 ℃ in a forced air drying oven, and the substrate is dried.

Secondly, spin-coating a hole transport layer; after the ultraviolet ozone treatment for 25min, the PEDOT: PSS aqueous solution filtered through a water-based 0.45 μm filter head was spin-coated on an ITO glass substrate at a speed of 5000rpm for 40s (thickness of about 40 nm), and baked at 150℃for 20min.

Then, carbon disulphide (CS) ₂ ) Preparing a photoactive layer solution by using a binary mixed solvent of Paraxylene (PX), weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in a mass ratio of 1:1.6 in air, and placing the solute in a glove box;

after that, CS was added in a glove box ₂ And PX binary mixed solvent, the concentration is prepared to be 13mg mL ^–1 CS in solvent ₂ The volume fraction was 97% and the volume fraction of PX was 3%. Stirring the mixed solution at 50 ℃ for 1 hour, spin-coating an active layer on the hole transport layer, and then performing thermal annealing treatment at 90 ℃ for 10min.

Subsequently, the electron transport layer was spin-coated, and after cooling the annealed active layer film to room temperature, a methanol solution of PDINO was stirred at room temperature overnight, pdino=2 mg mL ^–1 Casting at 3000rpm onto the active layer to formAnd a cathode interlayer (about 10 nm).

Finally, metal electrodes were evaporated, all samples were transferred to a vacuum chamber, and metal aluminum was deposited at 2×10 ^-4 Pa, and evaporating the pressure heat to the sample, wherein the thickness of aluminum is about 100nm, so as to obtain the device of the organic solar cell.

The photoelectric conversion efficiency of the organic solar cell was tested using a 3A solar simulator as a light source, and a digital source meter manufactured by Keithley2400 (gizzard co., usa).

Characterization analysis of the organic solar cell prepared in this example includes the following:

fig. 1: organic solar cell current density-voltage curve. After the organic solar cell device prepared by the invention uses the mixed non-halogenated solvent strategy, the photoelectric conversion efficiency of the device is obviously improved, as shown in figure 1. Compared to organic solar cells prepared using a single halogenated solvent and a single non-halogenated solvent, devices based on mixed non-halogenated solvents exhibit higher short-circuit current densities and fill factors, resulting in higher photoelectric conversion efficiencies. Finally, devices based on mixed non-halogenated solvents achieved 17.50% photoelectric conversion efficiency over single CS ₂ And 15.48% and 17.11% higher for the halogenated solvent CF treatment.

Fig. 2: an external quantum efficiency curve of an organic solar cell. From the EQE curve, it can be seen that relative to CS ₂ The treated devices, CF treated devices showed a slight red shift in the EQE spectrum and the EQE values were higher, whereas the mixed non-halogenated solvent treated resulting samples showed the most pronounced red shift in the EQE spectrum and a maximum in EQE between 610 and 800 nm. CF. CS (circuit switching) ₂ And integral J of hybrid non-halogenated solvent treated OSC device _SC Values of 24.27, 21.73 and 25.43mA cm, respectively ^-2 From the J-V plot, it was confirmed that J of the hybrid non-halogenated solvent treatment device _SC The value is high (error not exceeding 5%).

Table one: photovoltaic performance parameters of organic solar cell devices. As can be seen from the table, the blend film treated with CF had a PCE of 17.11% and an open circuit voltage of 0.913V, J _SC 25.0 of6mAcm ^-2 The fill factor was 74.82%. When using pure CS ₂ V as solvent _OC Obviously increase to 0.936V, and J _SC And FF drops to 22.46 and 73.61%, respectively, with PCE 15.48%. The PCE of the device prepared by the mixed non-halogenated solvent treatment is equivalent to that of halogenated solvent, the PCE of the device reaches 17.50 percent, V _OC 0.885V, J _SC The improvement is 26.25mA cm ^-2 FF is 75.30%.

TABLE 1

Fig. 3, photo-generated current density (J _ph ) -effective voltage (V _eff ) A curve. J of three organic solar cell devices _ph The value at low voltage follows V _eff And increases sharply, approaching saturation at high voltages. With CF and CS ₂ The treated devices (23.04 mA cm respectively ^-2 And 20.95mAcm ^-2 ) In contrast, the short-circuit photocurrent density J of the hybrid non-halogenated solvent treated device _ph,SC 23.42mA cm ^-2 (J _ph,SC J in short-circuit condition _ph ). In addition, the saturated photocurrent densities (J _ph,sat ) 24.85, 22.79 and 24.14mA cm respectively ^-2 (taking V according to experimental data _eff J at 3.0V _ph Is J _ph,sat ) Wherein CF, CS ₂ And the saturated photocurrent densities of the three devices treated with the mixed non-halogenated solvents were 92.72%, 91.93% and 97.06%, respectively. J of Mixed non-halogenated solvent treatment device _ph,SC /J _ph,sat The values are all significantly higher than other similar species, indicating that strategies of mixing non-halogenated solvents can significantly improve charge generation and collection efficiency. In addition, hybrid non-halogenated solvent treated organic solar cells exhibit a larger J _ph,SC And J _ph,SC /J _ph,sat Combination of values and maximum J tested in the J-V plot _SC The values are consistent.

FIG. 4, active layer blend film scanning probe microscopy (AFM) image. Wherein, (a) is shown in the embodiment of the inventionPhase diagram of the method and active layer blend film prepared by single non-halogenated solvent and halogenated solvent; (b) The figures are height views of the active layer blend films prepared by the method described in the examples of the present invention with a single non-halogenated solvent, halogenated solvent. At CS ₂ Large size phase separation was found in the treated blend film. In contrast, CF solvent treated blend films exhibited little phase separation, well mixed donor/acceptor domains. In addition, the small white fiber and black area of the mixed non-halogenated solvent treated blend film is significantly increased, and the formation of this finer fibrous D18 and L8-BO aggregates facilitates the construction of a two-channel network structure. The three different film morphological characteristics can be distinguished in the AFM height map, and the test result shows that CF and CS are used ₂ And CS (common services) ₂ Root mean square roughness (R) of blended film obtained by PX-containing treatment _q ) 0.92, 1.19 and 0.88nm, respectively. The active layer treated by the mixed non-halogenated solvent has a smoother surface, the reduction of roughness is consistent with the inhibition of L-L phase separation, and the moderate roughness is beneficial to the improvement of the device performance.

Fig. 5, a field emission ultra-high resolution Transmission Electron Microscope (TEM) image of an active layer blend film. The CF treated samples were uniformly white and black small areas, CS ₂ The treated samples showed significantly larger black and white regions, 50-100nm in size, indicating a significant increase in receptor and donor domains. In contrast, many white and black fiber bundles were uniformly present in the mixed non-halogenated solvent treated samples, indicating a dense arrangement of bicontinuous donor and acceptor aggregates.

FIG. 6 is a chemical structure of D18 and L8-BO used in the examples of the present invention.

FIG. 7 is a bar graph of the solubility of donor-acceptor used in the present invention in three pure solvents. L8-BO in CF, CS ₂ And PX with solubilities of 21.6, 31.8 and 47.0mg mL, respectively ^-1 The solubility difference is not large. D18 solubility in three different solvents varies widely, D18 in CS ₂ Gel can be formed, and the Critical Gelation Concentration (CGC) is 70.0mg mL ^-1 The solubility of D18 in PX is very limited, less than 0.01mg mL ^-1 。

Comparative example 1

The method for preparing the organic solar cell device through chlorine imitation of the single halogenated solvent comprises the following preparation steps:

preparation of photoactive layer blend solution using chloroform solvent: firstly, weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in air; thereafter, CF was added to prepare a total concentration of 9mg mL in a glove box ^-1 Stirring for 1 hour at 50 ℃, then heating to 100 ℃ and stirring for 10 minutes for standby;

the other steps are the same as in example 1.

Comparative example 2

The method for preparing the organic solar cell device by using the carbon disulfide as the single non-halogenated solvent in the embodiment comprises the following preparation steps:

preparation of photoactive layer blend solutions using carbon disulfide solvents: firstly, weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in air; after that, CS was added in a glove box ₂ Preparing the total concentration to be 13mg mL ^-1 Stirring for 1 hour at 50 ℃, and cooling to room temperature for standby;

the other steps are the same as in example 1.

The test results are shown in Table 1

The invention relates to the technical field of organic solar cells, in particular to a preparation method of an organic solar cell based on mixed non-halogenated solvent processing.

Step 1, cleaning an ITO glass substrate; step 2, spin-coating a hole transport layer; step 3, preparing a photoactive layer; step 4, spin coating an electron transport layer; step 5, evaporating a metal electrode; step 6, testing the photovoltaic performance; the organic solar cell device prepared by the hybrid non-halogenated solvent strategy forms an "ideal" thin film microstructure consisting of a bicontinuous phase-separated network with nanoscale domains and good pi-pi stacking, with the optimal morphology of the hybrid non-halogenated solvent resulting in significantly prolonged charge carrier kinetics, efficient exciton dissociation, and enhanced charge transport. Therefore, the photovoltaic performance of the non-halogenated solvent processing organic solar cell is effectively improved, a brand new strategy is provided for solving the high-efficiency preparation problem of the non-halogenated organic solar cell, and the process of converting the non-halogenated organic solar cell into industrialization is accelerated.

Example 2

In this example, the preparation process of the blend solution is:

carbon disulphide (CS) ₂ ) Preparing a photoactive layer solution by using a binary mixed solvent of Paraxylene (PX), weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in a mass ratio of 1:1 in air, and placing the solute in a glove box;

CS addition in glove box ₂ And PX binary mixed solvent, and the concentration is 10mg mL ^–1 CS in solvent ₂ The volume fraction was 95% and the volume fraction of PX was 5%. Stirring the mixed solution at 40 ℃ for 1.5 hours, spin-coating an active layer on the hole transport layer, and then performing thermal annealing treatment at 90 ℃ for 10min.

The same as in example 1 was repeated.

Example 3

In this example, the preparation process of the blend solution is:

carbon disulphide (CS) ₂ ) Preparing a photoactive layer solution by using a binary mixed solvent of Paraxylene (PX), weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in a mass ratio of 1:1.2 in air, and placing the solute in a glove box;

CS addition in glove box ₂ And PX binary mixed solvent, the concentration is 5mg mL ^–1 CS in solvent ₂ The volume fraction was 90% and the volume fraction of PX was 10%. Stirring the mixed solution at 35 ℃ for 1.5 hours, spin-coating an active layer on the hole transport layer, and then performing thermal annealing treatment at 90 ℃ for 10min.

The same as in example 1 was repeated.

Example 4

In this example, the preparation process of the blend solution is:

carbon disulphide (CS) ₂ ) Preparing a photoactive layer solution by using a binary mixed solvent of Paraxylene (PX), weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in a mass ratio of 1:1.5 in air, and placing the solute in a glove box;

CS addition in glove box ₂ And PX binary mixed solvent, and the concentration is 20mg mL ^–1 CS in solvent ₂ The volume fraction was 92% and the volume fraction of PX was 8%. Stirring the mixed solution at 45 ℃ for 1.5 hours, spin-coating an active layer on the hole transport layer, and then performing thermal annealing treatment at 90 ℃ for 10min.

The same as in example 1 was repeated.

Example 5

In this example, the preparation process of the blend solution is:

carbon disulphide (CS) ₂ ) Preparing a photoactive layer solution by using a binary mixed solvent of Paraxylene (PX), weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in a mass ratio of 1:1.8 in air, and placing the solute in a glove box;

CS addition in glove box ₂ And PX binary mixed solvent, the concentration is 8mg mL ^–1 CS in solvent ₂ The volume fraction was 96% and the volume fraction of PX was 4%. Stirring the mixed solution at 30 ℃ for 2 hours, spin-coating an active layer on the hole transport layer, and then performing thermal annealing treatment at 90 ℃ for 10min.

The same as in example 1 was repeated.

Example 6

In this example, the preparation process of the blend solution is:

carbon disulphide (CS) ₂ ) Preparing a photoactive layer solution by using a binary mixed solvent of Paraxylene (PX), weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in a mass ratio of 1:2 in air, and placing the solute in a glove box;

CS addition in glove box ₂ And PX binary mixed solvent, the concentration is 15mg mL ^–1 CS in solvent ₂ The volume fraction was 98% and the volume fraction of PX was 2%. Stirring the mixed solution at 45 ℃ for 1 hour, spin-coating an active layer on the hole transport layer, and then performing thermal annealing treatment at 90 ℃ for 10min.

The same as in example 1 was repeated.

Example 7

In this example, an active layer was spin-coated on the hole transport layer at 1000rpm, an annealing temperature of 50℃and an annealing time of 200min. The same as in example 1 was repeated.

Example 8

In this example, an active layer was spin-coated on the hole transport layer at 2000rpm, at 100℃for 60 minutes. The same as in example 1 was repeated.

Example 9

In this example, the active layer was spin-coated on the hole transport layer at 2000rpm, and no annealing was performed for 0. The same as in example 1 was repeated.

Example 10

In this example, an active layer was spin-coated on the hole transport layer at a spin speed of 1500rpm, an annealing temperature of 200℃and an annealing time of 10min. The same as in example 1 was repeated.

Example 11

Then, carbon disulphide (CS) ₂ ) Preparing a photoactive layer solution by using a binary mixed solvent of Paraxylene (PX), weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in a mass ratio of 1:1.6 in air, and placing the solute in a glove box;

after that, CS was added in a glove box ₂ And PX binary mixed solvent, the concentration is 5mg mL ^–1 CS in solvent ₂ The volume fraction was 97% and the volume fraction of PX was 3%. Stirring the mixed solution at 50deg.C for 1 hr, spin-coating on hole transport layer, rotating active layer at about 800rpm, and then feedingAnd carrying out thermal annealing treatment, wherein the annealing temperature is 90 ℃, and the annealing time is 10min. The active layer thickness was about 50nm. The same as in example 1 was repeated.

Example 12

Then, carbon disulphide (CS) ₂ ) Preparing a photoactive layer solution by using a binary mixed solvent of Paraxylene (PX), weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in a mass ratio of 1:1.6 in air, and placing the solute in a glove box;

after that, CS was added in a glove box ₂ And PX binary mixed solvent, and the concentration is 10mg mL ^–1 CS in solvent ₂ The volume fraction was 97% and the volume fraction of PX was 3%. The mixed solution was stirred at 50 c for 1 hour, an active layer was spin-coated on the hole transport layer at a rotation speed of about 1000rpm, and then heat-annealed at 90 c for 10 minutes. The active layer thickness was about 100nm. The same as in example 1 was repeated.

Example 13

Then, carbon disulphide (CS) ₂ ) Preparing a photoactive layer solution by using a binary mixed solvent of Paraxylene (PX), weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in a mass ratio of 1:1.6 in air, and placing the solute in a glove box;

after that, CS was added in a glove box ₂ And PX binary mixed solvent, the concentration is 15mg mL ^–1 CS in solvent ₂ The volume fraction was 97% and the volume fraction of PX was 3%. The mixed solution was stirred at 50 c for 1 hour, an active layer was spin-coated on the hole transport layer at a rotation speed of about 1000rpm, and then heat-annealed at 90 c for 10 minutes. The active layer thickness was about 200nm. The same as in example 1 was repeated.

Example 14

Then, carbon disulphide (CS) ₂ ) Preparing a photoactive layer solution by using a binary mixed solvent of Paraxylene (PX), weighing a solute organic polymer donor D18 and a non-fullerene small molecule acceptor L8-BO in a mass ratio of 1:1.6 in air, and mixingThe solute is placed in a glove box;

after that, CS was added in a glove box ₂ And PX binary mixed solvent, and the concentration is 20mg mL ^–1 CS in solvent ₂ The volume fraction was 97% and the volume fraction of PX was 3%. The mixed solution was stirred at 50 c for 1 hour, an active layer was spin-coated on the hole transport layer at a rotation speed of about 800rpm, and then heat-annealed at 90 c for 10 minutes. The active layer thickness was about 300nm. The same as in example 1 was repeated.

The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims (10)

1. A preparation method of a non-fullerene organic solar cell based on a non-halogenated mixed solvent is characterized by comprising the following steps of:

sequentially stacking and preparing an anode, a hole transport layer, a photoactive layer, an electron transport layer and a cathode;

the photoactive layer is prepared by coating a blending solution on the hole transport layer and annealing, wherein the solute of the blending solution is a mixture of an organic polymer donor D18 and a non-fullerene electron acceptor L8-BO, and the solvent is a mixed solution of carbon disulfide and p-xylene.

2. The method for preparing a non-fullerene organic solar cell based on a non-halogenated mixed solvent according to claim 1, wherein the mass ratio of the organic polymer donor D18 and the non-fullerene electron acceptor L8-BO in the solute is 1 (1-2).

3. The method for producing a non-fullerene organic solar cell based on a non-halogenated mixed solvent according to claim 1, wherein the concentration of the blending solution is 5 to 20 mg.ml ^–1 。

4. The method for preparing a non-fullerene organic solar cell based on a non-halogenated mixed solvent according to claim 1, wherein the mixing volume ratio of carbon disulfide and paraxylene in the solvent is (90-100): 1-10.

5. The method for producing a non-fullerene organic solar cell based on a non-halogenated mixed solvent according to claim 1, wherein the solute and the solvent are mixed in a glove box by the blending solution and stirred at 30 to 50 ℃ for 1 to 3 hours.

6. The method for preparing a non-fullerene organic solar cell based on non-halogenated mixed solvent according to claim 1, wherein the blending solution is spin-coated on the hole transport layer at a rotation speed of 600-3000rpm.

7. The method for preparing a non-fullerene organic solar cell based on a non-halogenated mixed solvent according to claim 1, wherein the annealing temperature is 50-200 ℃ and the annealing time is 0-120min.

8. The non-fullerene organic solar cell based on non-halogenated mixed solvent according to claim, wherein the photoactive layer is prepared by spin-coating the mixed solution on the hole transport layer at a rotation speed of 1200 rpm;

the preparation process of the mixed solution comprises the following steps: the method comprises the steps of mixing a solute and a solvent in a glove box, wherein the solute is a mixture of an organic polymer donor D18 and a non-fullerene electron acceptor L8-BO in a mass ratio of 1:1.6, the solvent is a mixed solution of carbon disulfide and p-xylene in a volume ratio of 97:3, and the concentration of the mixed solution is 13mg mL ^–1 The method comprises the steps of carrying out a first treatment on the surface of the And (3) stirring the mixed solution at 50 ℃ for 1h, and then carrying out annealing treatment at 90 ℃ for 10min to obtain the mixed solution.

9. A non-fullerene organic solar cell based on a non-halogenated mixed solvent, characterized by comprising:

an anode that collects holes;

a cathode for collecting electrons;

a photoactive layer between the anode and the cathode, the photoactive layer being a blend of a polymeric donor D18 and a non-fullerene electron acceptor L8-BO; the photoactive layer is prepared by a blending solution, wherein the solute of the blending solution is a mixed solution of a macromolecule donor D18 and a non-fullerene electron acceptor L8-BO, and the solvent is carbon disulfide and paraxylene;

a hole transport layer interposed between the anode and the photoactive layer;

an electron transport layer interposed between the cathode and the photoactive layer.

10. The non-fullerene-based organic solar cell according to claim 9, wherein the thickness of the photoactive layer is between 50nm and 300nm.