CN111740021A - Light emitting device and display panel - Google Patents
Light emitting device and display panel Download PDFInfo
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- CN111740021A CN111740021A CN202010600504.2A CN202010600504A CN111740021A CN 111740021 A CN111740021 A CN 111740021A CN 202010600504 A CN202010600504 A CN 202010600504A CN 111740021 A CN111740021 A CN 111740021A
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- 239000010410 layer Substances 0.000 claims abstract description 271
- 239000000463 material Substances 0.000 claims abstract description 135
- 239000002346 layers by function Substances 0.000 claims abstract description 25
- 230000000903 blocking effect Effects 0.000 claims description 19
- 150000004982 aromatic amines Chemical class 0.000 claims description 5
- 125000005259 triarylamine group Chemical group 0.000 claims description 5
- 239000000969 carrier Substances 0.000 abstract description 32
- 230000005540 biological transmission Effects 0.000 abstract description 25
- 238000010791 quenching Methods 0.000 abstract description 11
- 230000000171 quenching effect Effects 0.000 abstract description 11
- 238000009825 accumulation Methods 0.000 abstract description 9
- 235000019557 luminance Nutrition 0.000 description 33
- 238000010586 diagram Methods 0.000 description 22
- 238000002347 injection Methods 0.000 description 10
- 239000007924 injection Substances 0.000 description 10
- 238000004770 highest occupied molecular orbital Methods 0.000 description 7
- 238000004768 lowest unoccupied molecular orbital Methods 0.000 description 7
- 241001270131 Agaricus moelleri Species 0.000 description 4
- 230000005525 hole transport Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 230000005281 excited state Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
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- 239000000243 solution Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
Abstract
The invention discloses a light emitting device and a display panel. The light-emitting device comprises a first electrode, a functional layer and a second electrode which are arranged in a stacked manner; the functional layer includes a first light-emitting layer; the functional layer further comprises at least one film layer of a second light-emitting layer and an efficiency balancing layer; at least one of the first light emitting layer, the second light emitting layer, and the efficiency balancing layer includes a carrier rate balancing material. The carrier rate balance material is used for adjusting the transmission rate of carriers in the light-emitting layer, so that the difference of the transmission rates of the carriers in the light-emitting layer is reduced, the accumulation of the carriers in the light-emitting layer can be reduced, the exciton quenching in the light-emitting layer is reduced, the efficiency roll-off of the light-emitting device can be improved, and the change regularity of the curve of the luminous brightness and the luminous efficiency of the light-emitting device can be improved. When the display panel displays, the phenomenon of gray scale brightness jump when the display panel displays different gray scale brightness can be reduced, and the use experience of a user is improved.
Description
Technical Field
The embodiment of the invention relates to the technical field of display, in particular to a light-emitting device and a display panel.
Background
At present, the luminous efficiency of an Organic Light-Emitting Diode (OLED) is unstable, which causes a phenomenon of gray scale brightness jump in the display process of an OLED display panel, and affects the use effect of a customer.
Disclosure of Invention
The invention provides a light-emitting device and a display panel, which aim to improve the balance of the light-emitting efficiency of the light-emitting device and improve the phenomenon of gray scale brightness jump of the display panel.
In a first aspect, embodiments of the present invention provide a light emitting device, including a first electrode, a functional layer, and a second electrode, which are stacked; the functional layer includes a first light-emitting layer;
the functional layer further comprises at least one film layer of a second light-emitting layer and an efficiency balancing layer; at least one film layer of the first light emitting layer, the second light emitting layer, and the efficiency balancing layer includes a carrier rate balancing material.
Optionally, the first light emitting layer comprises a host material and a guest material; the difference between the energy level of the carrier rate balance material and the energy level of the guest material is less than or equal to 0.2 eV.
Optionally, the functional layer comprises at least one second light emitting layer; at least one of the first light emitting layer and the second light emitting layer comprises a carrier rate balancing material; the second light emitting layer is disposed adjacent to the first light emitting layer.
Optionally, the mass ratio of the carrier rate balancing material to the film layer is 0.1% -90%.
Optionally, the functional layer comprises at least one efficiency balancing layer; the efficiency balancing layer comprises a carrier rate balancing material; the efficiency balancing layer is disposed adjacent to the first light emitting layer.
Optionally, the thickness of the efficiency balancing layer is greater than or equal to 1nm and less than or equal to 50 nm.
Optionally, a ratio of a carrier mobility of the carrier rate balancing material to a carrier mobility of a host material of the first light emitting layer is greater than or equal to 10.
Optionally, the carrier rate balancing material comprises at least one of a spirofluorene derivative, an aromatic amine derivative and a triarylamine derivative.
Optionally, the light emitting device further comprises an electron blocking layer and a hole blocking layer; the electron blocking layer is disposed between the first electrode and the first light emitting layer, and the hole blocking layer is disposed between the second electrode and the first light emitting layer.
In a second aspect, embodiments of the present invention further provide a display panel including the light emitting device provided in any of the embodiments of the present invention.
According to the technical scheme of the embodiment of the invention, at least one film layer of the first light-emitting layer, the second light-emitting layer and the efficiency balance layer of the light-emitting device comprises the carrier rate balance material, and the carrier transmission rate in the light-emitting layer is adjusted by the carrier rate balance material, so that the difference of the transmission rates of electrons and holes in the light-emitting layer is reduced, the accumulation of carriers in the light-emitting layer can be reduced, the exciton quenching formed by the carriers in the light-emitting layer is reduced, the efficiency roll-off of the light-emitting device can be improved, and the change regularity of the curve of the light-emitting brightness and the light-emitting efficiency of the light-emitting device can be improved. When the display panel formed by the luminescent device is used for displaying, the difference value between the theoretical luminous brightness of the luminescent device corresponding to different gray-scale brightness of the display panel and the actual luminous brightness obtained by fitting the luminous brightness of the luminescent device through gamma binding points and the curve of the luminous efficiency is reduced, so that the phenomenon of gray-scale brightness jump when the display panel displays different gray-scale brightness can be reduced, and the use experience of a user is improved.
Drawings
FIG. 1 is a graph illustrating the luminance and efficiency of a conventional light emitting device;
fig. 2 is a schematic structural diagram of a light emitting device according to an embodiment of the present invention;
FIG. 3 is a graph illustrating a comparison of luminance versus luminous efficiency curves of different light emitting devices according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of another light-emitting device provided in an embodiment of the present invention;
fig. 5 is a schematic structural diagram of another light-emitting device provided in an embodiment of the present invention;
fig. 6 is a schematic structural diagram of another light-emitting device provided in an embodiment of the present invention;
fig. 7 is a schematic structural diagram of another light-emitting device provided in an embodiment of the present invention;
fig. 8 is a schematic structural diagram of another light-emitting device provided in an embodiment of the present invention;
fig. 9 is a schematic structural diagram of another light-emitting device provided in an embodiment of the present invention;
fig. 10 is a schematic structural view of another light-emitting device provided in an embodiment of the present invention;
fig. 11 is a schematic structural diagram of another light-emitting device provided in an embodiment of the present invention;
fig. 12 is a schematic structural diagram of another light-emitting device provided in an embodiment of the present invention;
fig. 13 is a schematic structural diagram of a display panel according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a graph illustrating the luminance and efficiency of a conventional light emitting device. As shown in fig. 1, the abscissa represents the light emission luminance, and the ordinate represents the light emission efficiency. Curve 01 is a diagram showing the relationship between the luminance and the luminous efficiency of the conventional light-emitting device. As can be seen from the curve 01, the light-emitting device has different light-emitting efficiencies at different light-emitting luminances. Especially, when the light emitting luminance is relatively low, the change of the light emitting efficiency of the light emitting device is relatively large, that is, the change regularity of the curve of the light emitting luminance and the light emitting efficiency of the light emitting device is poor. When the OLED display panel displays, the display panel can display different gray-scale brightness, and the different gray-scale brightness corresponds to different light-emitting brightness of the light-emitting device. The luminance of the light emitting device corresponding to different gray scale luminance of the display panel can be obtained by fitting the luminance and luminous efficiency curve of the light emitting device through gamma binding points. When the curve change regularity of the luminance and the luminous efficiency of the luminous device is poor, the actual luminance of the luminous device obtained by fitting the gamma binding point to the luminance and the luminous efficiency curve of the luminous device is different from the theoretical luminance of the luminous device corresponding to the gray-scale luminance, so that the phenomenon of gray-scale luminance jump exists when the OLED display panel displays different gray-scale luminance, and the use effect of a user is influenced. Exemplarily, when the display panel can display 0-255 gray scales, the gamma binding point can preset the light-emitting luminances of 20 light-emitting devices corresponding to different gray scales, and then the light-emitting luminances of the light-emitting devices corresponding to other gray scales can be obtained according to the curve fitting of the light-emitting device luminance and the light-emitting efficiency, so as to realize the display of the 0-255 gray scales of the OLED display panel. The curve changes of the luminance and the luminous efficiency of the light emitting device are irregular, and a certain difference exists between a fitted result and the curve of the luminance and the luminous efficiency of the light emitting device, so that the phenomenon of gray scale luminance jump exists when the OLED display panel displays different gray scale luminance, and the using effect of a user is influenced.
In view of the above technical problems, embodiments of the present invention provide a light emitting device. Fig. 2 is a schematic structural diagram of a light emitting device according to an embodiment of the present invention. As shown in fig. 2, the light emitting device includes a first electrode 110, a functional layer 120, and a second electrode 130 which are stacked; the functional layer 120 includes a first light emitting layer 121; the functional layer 120 further includes at least one film layer of a second light emitting layer 122 and an efficiency balance layer 123; at least one film layer of the first light emitting layer 121, the second light emitting layer 122, and the efficiency balance layer 123 includes a carrier rate balance material.
Specifically, the first electrode 110 may be an anode, and the second electrode 130 may be a cathode. The first light emitting layer 121 may be an organic light emitting layer. When a driving current is supplied to the light emitting device, holes are transported from the first electrode 110 toward the first light emitting layer 121, and electrons are transported from the second electrode 130 toward the first light emitting layer 121. The holes and the electrons are recombined in the first light emitting layer 121 to form excitons in an excited state, the excitons in the excited state are attenuated and release energy in the form of light, and the first light emitting layer 121 emits light.
When the functional layer 120 includes at least one film layer of the second light emitting layer 122 and the efficiency balance layer 123, at least one film layer of the second light emitting layer 122 and the efficiency balance layer 123 is disposed adjacent to the first light emitting layer 121. Moreover, at least one of the first light emitting layer 121, the second light emitting layer 122 and the efficiency balancing layer 123 includes a carrier rate balancing material, and the carrier rate balancing material can adjust the transmission rate of carriers in the first light emitting layer 121 and/or the second light emitting layer 122, so that the difference between the transmission rates of electrons and holes in the first light emitting layer 121 and/or the second light emitting layer 122 is reduced, thereby reducing the accumulation of carriers in the first light emitting layer 121 and/or the second light emitting layer 122, reducing exciton quenching formed by carriers in the first light emitting layer 121 and/or the second light emitting layer 122, improving the efficiency roll-off of the light emitting device, and further improving the regularity of change of the curve of the light emitting brightness and the light emitting efficiency of the light emitting device. When the display panel formed by the luminescent device is used for displaying, the difference value between the theoretical luminous brightness of the luminescent device corresponding to different gray-scale brightness of the display panel and the actual luminous brightness obtained by fitting the luminous brightness of the luminescent device through gamma binding points and the curve of the luminous efficiency is reduced, so that the phenomenon of gray-scale brightness jump when the display panel displays different gray-scale brightness can be reduced, and the use experience of a user is improved. Exemplarily, fig. 3 is a graph comparing the light-emitting brightness and the light-emitting efficiency of different light-emitting devices provided by the embodiment of the present invention. Wherein, the abscissa is the luminance and the ordinate is the luminous efficiency. As shown in fig. 3, a curve 1 is a curve of the luminance and the luminous efficiency of a conventional light emitting device, and a curve 2 is a curve of the luminance and the luminous efficiency of a light emitting device according to an embodiment of the present invention. According to the curve 1 and the curve 2, the change rule of the curve of the luminance and the luminous efficiency of the light emitting device corresponding to the curve 2 is stronger. When the display panel formed by the luminous devices corresponding to the curve 2 is used for displaying, the difference value between the theoretical luminous brightness of the luminous devices corresponding to different gray-scale brightness of the display panel and the actual luminous brightness obtained by the gamma binding point fitting luminous device and luminous efficiency curve is reduced, so that the phenomenon of gray-scale brightness jump when the display panel displays different gray-scale brightness can be reduced, and the use experience of a user is improved.
When the carrier rate balance material adjusts the carrier transport rate, it may be adjusted according to the type of the light emitting device. Illustratively, when the light emitting device is an electron type, the transmission rate of electrons in the light emitting device is greater than the transmission rate of holes, and at this time, the hole mobility of the carrier rate balancing material is greater than the hole mobility of the light emitting layer, so that the carrier rate balancing material can increase the hole mobility in the light emitting layer, and further can reduce the difference of the transmission rates of carriers in the light emitting layer, thereby reducing exciton quenching formed by the carriers in the light emitting layer, and thus can improve the efficiency roll-off of the light emitting device. When the light-emitting device is a hole type, the transmission rate of holes in the light-emitting device is greater than the electron transmission rate, at the moment, the electron mobility of the carrier rate balancing material is greater than that of the light-emitting layer, the carrier rate balancing material can improve the electron mobility in the light-emitting layer, and further the difference of the transmission rates of carriers in the light-emitting layer can be reduced, so that exciton quenching formed by the carriers in the light-emitting layer can be reduced, and the efficiency roll-off of the light-emitting device can be improved. Therefore, the phenomenon of gray scale brightness jump when the display panel displays different gray scale brightness can be reduced, and the use experience of a user is improved.
With continued reference to fig. 2, first light-emitting layer 121 includes a host material and a guest material; the difference between the energy level of the carrier rate balance material and the energy level of the guest material is less than or equal to 0.2 eV.
Specifically, in the process of emitting light in the light emitting layer, the host material transfers the acquired energy to the guest material, so that the guest material forms an excited state, thereby emitting light. When the functional layer 120 includes the second light emitting layer 122, the second light emitting layer 122 also includes a host material and a guest material, and the first light emitting layer 121 and the second light emitting layer 122 are simultaneously used for light emission, that is, both the first light emitting layer 121 and the second light emitting layer 122 function as light emitting layers. Because the first light-emitting layer 121 and/or the second light-emitting layer 122 include the carrier rate balancing material, the carrier rate balancing material may be used to adjust the rate at which the energy obtained by the host material is transferred to the guest material, that is, the rate at which the energy of the carrier in the light-emitting layer is transferred from the host material to the guest material, and further, the transmission rate of the carrier in the light-emitting layer may be adjusted, and the difference in the transmission rates of the carrier in the light-emitting layer may be reduced, so that the accumulation of the carrier in the light-emitting layer may be reduced, the exciton quenching formed by the carrier in the light-emitting layer may be reduced, the efficiency roll-off of the light-emitting device may be improved, and further, the change regularity of the. When the display panel formed by the luminescent device is used for displaying, the difference value between the theoretical luminous brightness of the luminescent device corresponding to different gray-scale brightness of the display panel and the actual luminous brightness obtained by fitting the luminous brightness of the luminescent device through gamma binding points and the curve of the luminous efficiency is reduced, so that the phenomenon of gray-scale brightness jump when the display panel displays different gray-scale brightness can be reduced, and the use experience of a user is improved. When the difference between the energy level of the carrier rate balance material and the energy level of the guest material is less than or equal to 0.2eV, the energy of the host material in the light-emitting layer can be firstly transmitted to the carrier rate balance material and then transmitted to the guest material through the carrier rate balance material, so that the transmission path of the energy of the host material in the light-emitting layer can be adjusted, the difference of the transmission rates of the carriers in the light-emitting layer can be adjusted, the accumulation of the carriers in the light-emitting layer is reduced, the exciton quenching formed by the carriers in the light-emitting layer is reduced, and the efficiency roll-off of the light-emitting device is improved. The energy level of the carrier rate balance material is the difference between the Lowest Unoccupied Molecular Orbital (LUMO) energy level and the Highest Occupied Molecular Orbital (HOMO) energy level of the carrier rate balance material, and the energy level of the guest material is the difference between the LUMO energy level and the HOMO energy level of the guest material.
When the functional layer 120 includes the efficiency balance layer 123, the carrier rate balance material included in the efficiency balance layer 123 can adjust the rate at which the carriers are transmitted to the first light-emitting layer 121, and further, the difference of the carrier transmission rates in the first light-emitting layer 121 can be reduced according to the carrier transmission rate, so that the accumulation of the carriers in the first light-emitting layer 121 can be reduced, exciton quenching formed by the carriers in the light-emitting layer is reduced, the efficiency roll-off of the light-emitting device is improved, and further, the change regularity of the curve of the light-emitting brightness and the light-emitting efficiency of the light-emitting device can be improved. Therefore, the phenomenon of gray scale brightness jump when the display panel displays different gray scale brightness can be reduced, and the use experience of a user is improved. When the difference between the energy level of the carrier rate balancing material and the energy level of the guest material is less than or equal to 0.2eV, the rate of energy transfer for exciting the guest material to emit light can be adjusted, so that the accumulation of carriers in the light emitting layer can be reduced, the exciton quenching formed by the carriers in the light emitting layer can be reduced, and the efficiency roll-off of the light emitting device can be improved.
Note that the difference between the energy level of the carrier rate balance material and the energy level of the guest material of 0.2eV or less may include two cases, that is, the energy level of the carrier rate balance material is greater than the energy level of the guest material, or the energy level of the carrier rate balance material is less than the energy level of the guest material. Illustratively, the LUMO level of the carrier rate balancing material may be-3.0 eV, the HOMO level may be-6.0 eV, and the level of the carrier rate balancing material is-3.0 eV- (-6.0eV) to 3.0 eV. The LUMO level of the guest material may be-3.0 eV, the HOMO level may be-5.9 eV, and the level of the guest material is-3.0 eV- (-5.9eV) to 2.9 eV. The energy level of the carrier rate balancing material is greater than the energy level of the guest material and the difference is less than 0.2 eV. Alternatively, the LUMO level of the carrier rate balancing material may be-2.7 eV and the HOMO level may be-5.4 eV, and the level of the carrier rate balancing material is-2.7 eV- (-5.4eV) to 2.7 eV. The LUMO level of the guest material may be-2.8 eV, the HOMO level may be-5.6 eV, and the level of the guest material is-2.8 eV- (-5.6eV) to 2.8 eV. The energy level of the carrier rate balancing material is less than the energy level of the guest material and the difference is less than 0.2 eV.
Fig. 4 is a schematic structural diagram of another light-emitting device according to an embodiment of the present invention. As shown in fig. 4, fig. 4 exemplarily shows that the functional layer 120 includes at least one second light emitting layer 122; at least one of the first light emitting layer 121 and the second light emitting layer 122 includes a carrier rate balancing material; the second light emitting layer 122 is disposed adjacent to the first light emitting layer 121.
Specifically, as shown in fig. 4, when the first light emitting layer 121 and the second light emitting layer 122 simultaneously include the carrier rate balancing material, the carrier rate balancing material is distributed in the light emitting layer of the light emitting device. At this time, the carrier rate balance material may be doped in the light emitting layer of the light emitting device as a whole, thereby realizing that the first light emitting layer 121 and the second light emitting layer 122 simultaneously include the carrier rate balance material. The light-emitting layer comprises the carrier rate balancing material, so that the carrier rate balancing material can adjust the rate of transferring the energy of the carriers in the light-emitting layer from the host material to the guest material, further adjust the transmission rate of the carriers in the light-emitting layer, reduce the difference of the transmission rates of the carriers in the light-emitting layer, further reduce the accumulation of the carriers in the light-emitting layer, reduce exciton quenching formed by the carriers in the light-emitting layer, improve the efficiency roll-off of the light-emitting device, and further improve the change regularity of the curves of the light-emitting brightness and the light-emitting efficiency of the light-emitting device. When the display panel formed by the luminescent device is used for displaying, the phenomenon of gray scale brightness jump when the display panel displays different gray scale brightness can be reduced, and the use experience of a user is improved.
Fig. 5 is a schematic structural diagram of another light-emitting device according to an embodiment of the present invention. As shown in fig. 5, when the second light emitting layer 122 includes the carrier rate balance material, a structure in which the light emitting layer of the light emitting device is divided into the first light emitting layer 121 and the second light emitting layer 122 includes the carrier rate balance material may be achieved by doping a part of the film layer of the light emitting device with the carrier rate balance material. When the second light emitting layer 122 includes the carrier rate balancing material, the carrier rate balancing material can also adjust the rate at which the energy of the carrier in the light emitting layer is transferred from the host material to the guest material, so that the phenomenon of gray scale brightness jump when the display panel displays different gray scale brightness is reduced, and the use experience of a user is improved.
It is to be noted that fig. 5 only exemplarily shows that the second light-emitting layer 122 is disposed between the first light-emitting layer 121 and the first electrode 110. In other embodiments, the second light emitting layer 122 may also be disposed between the first light emitting layer 121 and the second electrode 130. Exemplarily, fig. 6 is a schematic structural diagram of another light emitting device provided in the embodiment of the present invention. As shown in fig. 6, the second light emitting layer 122 is disposed between the first light emitting layer 121 and the second electrode 130. In addition, fig. 7 is a schematic structural diagram of another light emitting device provided in the embodiment of the present invention. As shown in fig. 7, the functional layer 120 may further include two second light emitting layers 122 respectively disposed on both sides of the first light emitting layer 121. The second light emitting layer 122 can simultaneously adjust the rate of transferring the energy of the current carrier in the light emitting layer from the host material to the guest material from the two sides of the first light emitting layer 121, so that the phenomenon of gray scale brightness jump when the display panel displays different gray scale brightness is reduced, and the use experience of a user is improved. In the embodiment, fig. 8 is a schematic structural diagram of another light emitting device provided in the embodiment of the present invention. As shown in fig. 8, the functional layer 120 may further include two first light emitting layers 121, the first light emitting layers 121 are respectively disposed on two sides of the second light emitting layer 122, and the second light emitting layer 122 may also adjust a rate at which energy of carriers in the light emitting layers is transferred from the host material to the guest material, so as to reduce a phenomenon of gray scale luminance jump when the display panel displays different gray scale luminances, and improve user experience.
On the basis of the technical schemes, the mass ratio of the carrier rate balancing material to the film layer is 0.1-90%.
Specifically, when the carrier rate balance material is included in each of the first light-emitting layer 121 and the second light-emitting layer 122, that is, when the light-emitting layers of the light-emitting device include the carrier rate balance material, the mass ratio of the carrier rate balance material in the light-emitting layers is 0.1% to 90%. When the second light emitting layer 122 includes the carrier rate balance material, the mass ratio of the carrier rate balance material to the second light emitting layer 122 is 0.1% to 90%. The mass ratio of the carrier rate balancing material to the film layer where the carrier rate balancing material is located is set to be 0.1% -90%, the capability of the carrier rate balancing material in adjusting the carrier rate can be guaranteed, and meanwhile, the problem that the luminescent efficiency and the service life of the luminescent layer are low due to the fact that too much carrier rate balancing material is doped in the luminescent layer can be avoided.
Fig. 9 is a schematic structural diagram of another light-emitting device according to an embodiment of the present invention. As shown in fig. 9, the functional layer 120 includes at least one efficiency balancing layer 123; the efficiency balancing layer 123 includes a carrier rate balancing material; the efficiency balancing layer 123 is disposed adjacent to the first light emitting layer 121.
Specifically, fig. 9 exemplarily shows that the functional layer 120 includes a layer of efficiency balancing layer 123, and the carrier rate balancing material in the efficiency balancing layer 123 can adjust the rate of carrier transmission to the first light emitting layer 121, so as to reduce the difference of the carrier transmission rate in the first light emitting layer 121 according to the carrier transmission rate, thereby reducing the accumulation of the carrier in the first light emitting layer 121, reducing exciton quenching formed by the carrier in the light emitting layer, improving the efficiency roll-off of the light emitting device, reducing the phenomenon of gray-scale luminance jump when the display panel displays different gray-scale luminances, and improving the user experience.
Note that fig. 9 exemplarily shows that the efficiency balance layer 123 is disposed between the first light-emitting layer 121 and the first electrode 110. Fig. 10 is a schematic structural diagram of another light-emitting device according to an embodiment of the present invention. As shown in fig. 10, the efficiency balancing layer 123 may also be disposed between the first light emitting layer 121 and the second electrode 130. The difference in the carrier transport rates in the first light-emitting layer 121 can also be reduced from the other side of the first light-emitting layer 121, improving the efficiency roll-off of the light-emitting device.
In other embodiments, fig. 11 is a schematic structural diagram of another light emitting device provided in an embodiment of the present invention. As shown in fig. 11, the functional layer 120 may further include two efficiency balance layers 123 respectively disposed at both sides of the first light emitting layer 121. At this time, the difference of the carrier transport rates in the first light emitting layer 121 can be reduced from both sides of the first light emitting layer 121, and the efficiency roll-off of the light emitting device can be improved.
On the basis of the technical scheme, the thickness of the efficiency balancing layer is greater than or equal to 1nm and less than or equal to 50 nm.
In particular, the thickness of the efficiency balancing layer is related to the ability of the efficiency balancing layer to adjust the transport rate of carriers. The greater the thickness, the greater the ability of the efficiency balancing layer to adjust the transport rate of carriers. Meanwhile, the thickness of the efficiency balance layer affects the life span and luminous efficiency of the light emitting device. When the efficiency balance layer is thicker, the service life and the luminous efficiency of the light-emitting device are lower, so that the thickness of the efficiency balance layer can be set to be greater than or equal to 1nm and less than or equal to 50nm, the capability of the efficiency balance layer for adjusting the transmission rate of carriers can be ensured, and the service life and the luminous efficiency of the light-emitting device can be considered at the same time.
On the basis of the above technical solutions, the ratio of the carrier mobility of the carrier rate balancing material to the carrier mobility of the host material of the first light emitting layer is greater than or equal to 10.
In particular, the carrier rate balancing material may be provided in the second light emitting layer and/or the efficiency balancing layer, i.e. the carrier rate balancing material is adjacent to the host material of the light emitting layer, which may interact with the host material of the light emitting layer. When the carrier mobility of the carrier rate balancing material is greater than the carrier mobility of the host material of the first light emitting layer, the interaction of the carrier rate balancing material with the host material of the light emitting layer may increase the mobility of carriers through the host material of the light emitting layer, so that the transmission rate of carriers may be adjusted by the carrier rate balancing material. Alternatively, the ratio of the carrier mobility of the carrier rate balance material to the carrier mobility of the host material of the first light emitting layer is greater than or equal to 10, in which case the transport rate of carriers can be adjusted in a wider range by the carrier rate balance material.
The carrier mobility of the carrier rate balancing material may be either hole mobility or electron mobility. When the light emitting device is of an electron type, that is, when the electron mobility is greater than the hole mobility in the light emitting layer, the carrier mobility of the carrier rate balancing material may be a hole mobility, thereby improving the hole mobility in the light emitting layer. When the light emitting device is a hole type, that is, when hole mobility is greater than electron mobility in the light emitting layer, carrier mobility of the carrier rate balancing material may be electron mobility, thereby improving electron mobility in the light emitting layer.
On the basis of the technical schemes, the carrier rate balancing material comprises at least one of spirofluorene derivatives, aromatic amine derivatives and triarylamine derivatives.
Specifically, when at least one of the first light emitting layer and the second light emitting layer of the light emitting device includes a carrier rate balancing material, at least one of the spirofluorene-based derivative, the aromatic amine derivative, and the triarylamine derivative may be doped into the light emitting layer. When the light emitting device includes the efficiency balance layer, the material of the efficiency balance layer may include at least one of a spirofluorene-based derivative, an aromatic amine derivative, and a triarylamine derivative.
Fig. 12 is a schematic structural diagram of another light-emitting device according to an embodiment of the present invention. As shown in fig. 12, the light emitting device may further include an electron blocking layer 140 and a hole blocking layer 150; the electron blocking layer 140 is disposed between the first electrode 110 and the first light emitting layer 121, and the hole blocking layer 150 is disposed between the second electrode 130 and the first light emitting layer 121.
Specifically, the electron blocking layer 140 is disposed between the first electrode 110 and the first light emitting layer 121, and is used for blocking electrons transmitted from the second electrode 130 to the first light emitting layer 121 in the first light emitting layer 121, so as to improve the light emitting efficiency of the light emitting device. The hole blocking layer 150 is disposed between the second electrode 130 and the first light emitting layer 121, and is used to block holes, which are transmitted from the first electrode 110 to the first light emitting layer 121, in the first light emitting layer 121, so as to improve the light emitting efficiency of the light emitting device.
With continued reference to fig. 12, the light emitting device may further include a hole injection layer 160, a hole transport layer 170, an electron injection layer 180, and an electron transport layer 190. The hole injection layer 160 is disposed between the first electrode 110 and the electron blocking layer 140, and the hole transport layer 170 is disposed between the hole injection layer 160 and the electron blocking layer 140. The hole injection layer 160 serves to improve the injection capability of the holes provided from the first electrode 110, and the hole transport layer 170 serves to improve the hole transport capability, thereby improving the light emitting efficiency of the light emitting device. The electron injection layer 180 is disposed between the second electrode 130 and the hole blocking layer 150, the electron transport layer 190 is disposed between the electron injection layer 180 and the hole blocking layer 150, the electron injection layer 180 is used for improving the injection capability of electrons provided by the second electrode 130, and the electron transport layer 190 is used for improving the electron transport capability, so that the light emitting efficiency of the light emitting device is improved.
The embodiment of the invention also provides a display panel. Fig. 13 is a schematic structural diagram of a display panel according to an embodiment of the present invention. As shown in fig. 13, the display panel 10 includes a light emitting device 101 provided in any embodiment of the present invention.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A light-emitting device is characterized by comprising a first electrode, a functional layer and a second electrode which are arranged in a stacked manner; the functional layer includes a first light-emitting layer;
the functional layer further comprises at least one film layer of a second light-emitting layer and an efficiency balancing layer; at least one film layer of the first light emitting layer, the second light emitting layer, and the efficiency balancing layer includes a carrier rate balancing material.
2. The light-emitting device according to claim 1, wherein the first light-emitting layer comprises a host material and a guest material; the difference between the energy level of the carrier rate balance material and the energy level of the guest material is less than or equal to 0.2 eV.
3. A light-emitting device according to claim 2, wherein the functional layer comprises at least one second light-emitting layer; at least one of the first light emitting layer and the second light emitting layer comprises a carrier rate balancing material; the second light emitting layer is disposed adjacent to the first light emitting layer.
4. The light-emitting device according to claim 3, wherein the carrier rate balance material accounts for 0.1-90% of the film layer.
5. A light emitting device according to claim 2, wherein the functional layer comprises at least one efficiency balancing layer; the efficiency balancing layer comprises a carrier rate balancing material; the efficiency balancing layer is disposed adjacent to the first light emitting layer.
6. The light-emitting device according to claim 5, wherein the thickness of the efficiency balancing layer is greater than or equal to 1nm and less than or equal to 50 nm.
7. A light-emitting device according to claim 3 or 5, wherein the ratio of the carrier mobility of the carrier rate balancing material to the carrier mobility of the host material of the first light-emitting layer is greater than or equal to 10.
8. The light-emitting device according to claim 1, wherein the carrier rate balancing material comprises at least one of a spirofluorene-based derivative, an aromatic amine derivative, and a triarylamine derivative.
9. The light-emitting device according to claim 2, further comprising an electron blocking layer and a hole blocking layer; the electron blocking layer is disposed between the first electrode and the first light emitting layer, and the hole blocking layer is disposed between the second electrode and the first light emitting layer.
10. A display panel comprising the light-emitting device according to any one of claims 1 to 9.
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| CN202010600504.2A CN111740021A (en) | 2020-06-28 | 2020-06-28 | Light emitting device and display panel |
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| CN202010600504.2A CN111740021A (en) | 2020-06-28 | 2020-06-28 | Light emitting device and display panel |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022188457A1 (en) * | 2021-03-08 | 2022-09-15 | 京东方科技集团股份有限公司 | Light-emitting device, light-emitting substrate, and light-emitting apparatus |
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| CN105895819A (en) * | 2016-04-28 | 2016-08-24 | 京东方科技集团股份有限公司 | OLED device, preparation method therefor, and OLED display panel |
| CN110776496A (en) * | 2019-11-18 | 2020-02-11 | 苏州久显新材料有限公司 | 3, 4-diazaspiro fluorene derivative and synthesis method thereof, and electronic device containing 3, 4-diazaspiro fluorene derivative |
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| CN105895819A (en) * | 2016-04-28 | 2016-08-24 | 京东方科技集团股份有限公司 | OLED device, preparation method therefor, and OLED display panel |
| CN110776496A (en) * | 2019-11-18 | 2020-02-11 | 苏州久显新材料有限公司 | 3, 4-diazaspiro fluorene derivative and synthesis method thereof, and electronic device containing 3, 4-diazaspiro fluorene derivative |
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| WO2022188457A1 (en) * | 2021-03-08 | 2022-09-15 | 京东方科技集团股份有限公司 | Light-emitting device, light-emitting substrate, and light-emitting apparatus |
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Application publication date: 20201002 |