Optoelectrically active layer, method for preparing same and use thereof

Abstract

The present application relates to a kind of photoelectric active layer and its preparation method and application, the photoelectric active layer includes p-type polymer donor material, n-type non-fullerene acceptor material and p-type organic conjugated small molecule donor material.The present application is by introducing organic conjugated small molecule donor material into polymer donor material non-fullerene material acceptor material system, constructs three-phase body photoelectric active layer structure, further forms solar cell, by the mutual solubility between the third component material and host donor / acceptor material, realize to the aggregation characteristics of three-phase body system photoelectric active layer material, energy disorder degree and energy loss etc.are regulated, to achieve the purpose of simultaneously reducing band gap width and open-circuit voltage loss.Further improve the energy conversion efficiency of organic thin-film solar cell.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a photoelectric active layer and a preparation method and application thereof. BACKGROUND

[0002] Organic solar cells (OSCs) have attracted extensive attention due to their solution processability, flexibility, lightweight, and other characteristics, and are an important option for green and clean energy supply. In recent years, the rapid development of narrow-bandgap materials such as fused-ring non-fullerene acceptors (e.g., Y6 series molecules) has accelerated the speed of improving the energy conversion efficiency of organic solar cell devices.

[0003] In the prior art, such as C. Li, J. Zhou, J. Song, J. Xu, H. Zhang, X. Zhang, J. Guo, L. Zhu, D. Wei, G. Han, J. Min, Y. Zhang, Z. Xie, Y. Yi, H. Yan, F. Gao, F. Liu, Y. Sun, Nat. Energy. 2021, 6, 605, the energy conversion efficiency of an organic solar device prepared by using an organic polymer as a donor and a non-fullerene as an acceptor material has been improved to more than 18%; in comparison, the performance of an organic solar cell device using an organic small molecule as a donor material is slightly lagging behind, but the best energy conversion efficiency reported so far is more than 16%, such as L. Zhang, X. Zhu, D. Deng, Z. Wang, Z. Zhang, Y. Li, J. Zhang, K. Lv, L. Liu, X. Zhang, H. Zhou, H. Ade, Z. Wei, Adv. Mater. 2022, 34, 2106316.

[0004] Compared with binary devices, the rational design of ternary systems further improves the energy conversion efficiency of single-junction organic solar cell devices, and the best energy conversion efficiency of ternary organic solar cell devices reported so far has also been improved to nearly 19%, such as L. Zhan, S. Li, Y. Li, R. Sun, J. Min, Z. Bi, W. Ma, Z. Chen, G. Zhou, H. Zhu, M. Shi, L. Zuo, H. Chen, Joule 2022, 6, 1-14; S. Bao, H. Yang, H. Fan, J. Zhang, Z. Wei, C. Cui, Y. Li, Adv. Mater. 2021, 33, 2105301.

[0005] So far, the short-circuit current (J sc) and fill factor (FF) have reached 80% and 90% of the Shockley-Queisser (SQ) limit, only open-circuit voltage (V oc ) values are below 80% of the SQ limit. Further simultaneous improvement of open-circuit voltage and short-circuit current is of great significance for breakthrough in energy conversion efficiency of organic solar cell devices.

[0006] Based on Y6 series non-fullerene acceptor materials, the spectral utilization range has been widened to the near-infrared region, significantly improving the photon collection ability of the active layer of the organic solar cell. However, the decrease in the band gap means the decrease in the difference between the highest occupied molecular orbital (HOMO) energy level of the donor material and the lowest unoccupied molecular orbital (LUMO) energy level of the acceptor material, which will lead to the decrease in the open-circuit voltage of the device. Therefore, the use of reducing the band gap of organic photovoltaic materials to improve the J sc is limited, which is in competition with the growth of V oc , which is an obstacle to further improve the efficiency of organic solar cell devices. If the band gap can be further reduced in the existing high-efficiency narrow-band-gap organic photovoltaic material system without losing or even improving the V oc of the device, it is of great importance to break through the band gap limitation of organic photovoltaic materials and further improve the energy conversion efficiency of OSC devices. However, it is a difficult problem to reduce the band gap of the active layer material while not losing the V oc at the same time in the same system, and currently there is no effective strategy reported.

[0007] In summary, it is of great importance to develop an active material that can reduce the band gap and V oc loss at the same time in the same system. SUMMARY

[0008] In view of the deficiencies of the prior art, the purpose of the present application is to provide a photoelectric active layer, a preparation method and application thereof. The photoelectric active layer is constructed by introducing an organic conjugated small molecule donor material into a polymer donor material non-fullerene material acceptor material system to form a three-phase body photoelectric active layer structure, and further form a solar cell. By adjusting the mutual solubility between the third component material and the host donor / acceptor material, the aggregation characteristics, energy disorder degree and energy loss of the photoelectric active layer material of the three-phase body system are adjusted, and the purpose of simultaneously reducing the band gap width and the open-circuit voltage loss is achieved. The energy conversion efficiency of the organic thin film solar cell is further improved.

[0009] To achieve this purpose, the technical scheme adopted by the present application is as follows:

[0010] In a first aspect, the present application provides a photoelectric active layer, which comprises a p-type polymer donor material, an n-type non-fullerene acceptor material and a p-type organic conjugated small molecule donor material.

[0011] In the present application, the photoelectric active layer belongs to a three-phase system active layer, which is composed of two p-type organic semiconductor materials and one n-type non-fullerene derivative. The band gap and open-circuit voltage loss of the active layer material of the solar cell device with the three-phase active layer structure are reduced at the same time, and the energy conversion efficiency of the device is significantly improved. The reason is that in the traditional polymer donor / dual acceptor system ternary organic solar cell system, the better mutual solubility of the two acceptor materials will lead to the EQE band edge of the ternary system usually determined by the band edge of the material with a narrower band gap among the two acceptors. The increase of the proportion of the second non-fullerene acceptor with a wider band gap may even cause the blue shift of the EQE band edge of the ternary system. This is not conducive to the V oc At the same time of the loss reduction, the band gap of the active layer material is reduced (i.e. the red shift of the EQE curve band edge). Compared with the polymer donor / dual acceptor system, the ternary system of the double donor material / non-fullerene acceptor material of the present application provides the possibility for further reduction of the band gap of the active layer of the device. The adjustment of the aggregation state of the non-fullerene acceptor material may cause the red shift of the absorption band edge of the active layer material of the three-phase system device, thereby realizing the improvement of the short-circuit current of the device; at the same time, the optimization of the molecular arrangement order in the active layer and the regulation of the charge transfer state of the system may reduce the energy loss of the device and realize the synergistic improvement of the short-circuit voltage. Finally, the efficiency of the organic solar cell is further broken through.

[0012] In the present application, the p-type polymer donor material includes but is not limited to a D-A type polymer.

[0013] Preferably, the p-type polymer donor material includes any one of PM6, PTQ10, PM7, PM7-Si or PB-2F or a combination of at least two thereof. Typically but not limitatively, the combination includes a combination of PM6 and PTQ10, a combination of PM7, PM7-Si and PB-2F, a combination of PTQ10, PM7, PM7-Si and PB-2F, etc.

[0014] In the present application, the structure formula of the above-mentioned p-type polymer donor material is as follows:

[0015]

[0016] Preferably, the n-type non-fullerene acceptor material comprises any one of Y6, a derivative of Y6, L8BO, QX1, QX2, BTP-eC9, BTP-S9, m-BTP-Phc6, BTP-4Cl or BTP-S14 or a combination of at least two of them, wherein typical but non-limiting combinations include: a combination of Y6, a derivative of Y6 and L8BO, a combination of L8BO, QX1, QX2 and BTP-eC9, a combination of BTP-S9, m-BTP-Phc6, BTP-4Cl, BTP-S9 and BTP-S14, and the like, further preferably any one of Y6, L8BO, QX1 or QX2 or a combination of at least two of them.

[0017] In the present application, the n-type non-fullerene acceptor material has the following structural formula:

[0018]

[0019]

[0020]

[0021]

[0022] Preferably, the p-type organic conjugated small molecule donor material comprises any one of BTID-2F, ZR1, P-PhS, M-PhS, BTR-CL, M-PhI, M-PhI-F, M-PhI-2F, P-PhI, P-PhI-F or P-PhI-2F or a combination of at least two of them, wherein typical but non-limiting combinations include: a combination of BTID-2F and ZR1, a combination of P-PhS, M-PhS, BTR-CL and M-PhI, a combination of P-PhI, P-PhI-F and P-PhI-2F, a combination of P-PhS, M-PhS, BTR-CL, M-PhI, M-PhI-F, M-PhI-2F, P-PhI and P-PhI-F, and the like.

[0023] In the present application, the p-type organic conjugated small molecule donor material has the following structural formula:

[0024]

[0025]

[0026] wherein the general formula of M-PhS is as above, X is Y is H;

[0027] The general formula of P-PhS is as above, Y is X is H;

[0028] " is a linking site.

[0029]

[0030]

[0031] wherein the general formula of M-PhI is as above, X is Y, A, B are selected from H;

[0032] the general formula of P-PhI is as above, Y is X, A, B are selected from H;

[0033] the general formula of M-PhI-F is as above, X is Y, B are selected from H, A is selected from F;

[0034] the general formula of M-PhI-2F is as above, X is Y is selected from H, A and B are selected from F;

[0035] the general formula of P-PhI-2F is as above, Y is X is selected from H, A and B are selected from F;

[0036] " is a linking site.

[0037] Preferably, the mass percentage of the p-type organic conjugated small molecule donor material is 1wt%-99wt%, for example 6wt%, 11wt%, 18wt%, 25wt%, 48wt%, 68wt%, 87wt%, 92wt%, 99wt% and the like, further preferably 6wt%-95wt%, based on the total mass of 100wt% of the p-type polymer donor material and the p-type organic conjugated small molecule donor material.

[0038] Preferably, the thickness of the yellow point active layer is 40-400nm, for example 42nm, 77nm, 122nm, 163nm, 204nm, 278nm, 397nm and the like.

[0039] In a second aspect, the present application provides a preparation method of the photoelectric active layer of the first aspect, the preparation method of the photoelectric active layer comprising the following steps:

[0040] The p-type polymer donor material and the p-type organic conjugated small molecule donor material are mixed, and then mixed with the n-type non-fullerene acceptor material, and then mixed with an organic solvent, and the mixed solution is coated on a substrate, dried to form the photoelectric active layer.

[0041] Preferably, the organic solvent is any one or a combination of at least two of chloroform, toluene, chlorobenzene or o-dichlorobenzene.

[0042] Preferably, the mixed solution further comprises an additive.

[0043] Preferably, the additive comprises any one or a combination of chloronaphthalene, 1,8-2-iodooctane or TPE material, wherein a typical but non-limiting combination includes a combination of chloronaphthalene and 1,8-2-iodooctane, a combination of 1,8-2-iodooctane and TPE material, a combination of chloronaphthalene, 1,8-2-iodooctane and TPE material, etc.

[0044] Preferably, the drying temperature is 20-200℃ (e.g. 35℃, 43℃, 49℃, 65℃, 112℃, 198℃, etc.) and the time is 0.05-48h (e.g. 0.1h, 0.2h, 0.4h, 0.6h, 0.8h, 1h, 1.2h, 1.4h, 1.6h, 1.8h, etc.).

[0045] In the present application, the coating includes spin coating and / or blade coating.

[0046] In the present application, for the p-type donor material in the photoelectric active layer, the small molecule material is incorporated into the system with polymer material as the host material as the "guest material", which can improve the crystallinity of the polymer, and finally realize the improvement of the charge transport and collection of the three-phase system and the filling factor.

[0047] In the present application, since the small molecule material is used as the "guest material" in the donor material of the photoelectric active layer, there is a difference in the mutual solubility of the host polymer donor and the host non-fullerene acceptor small molecule, and the proportion of the mixed non-fullerene acceptor small molecule also differs. However, the small molecule guest donor material changes the aggregation state of the non-fullerene acceptor molecule, the reduction of the intermolecular packing distance and the increase of the molecular coherence length of the acceptor molecule will lead to the improvement of the aggregation degree, and then realize the red shift of the external quantum efficiency (EQE) curve band edge of the active layer material, and the improvement of the short-circuit current of the three-phase system organic solar cell material. At the same time, the introduction of the high-crystalline organic conjugated small molecule "guest" donor material can also improve the arrangement order degree of the donor and acceptor molecules in the active layer, reduce the energy loss of the device, and realize the synergistic improvement of the short-circuit voltage; through the development of the universal third component organic photovoltaic material, an effective way is provided for further breakthrough of the efficiency of organic solar cells.

[0048] Generally, the use of reducing the band gap of the active layer material of the organic solar cell device has widened the spectral utilization range to the near-infrared region, and significantly improved the photon collection ability of the active layer of the organic solar cell. However, the reduction of the band gap means the decrease of the difference between the highest occupied molecular orbital (HOMO) energy level of the donor material and the lowest unoccupied molecular orbital (LUMO) energy level of the acceptor material, which will lead to the reduction of the open-circuit voltage of the device. The use of reducing the band gap of the organic photovoltaic material to improve the Jsc is limited, which competes with the growth of V oc . That is, a significant increase in J sc comes at the expense of V oc . However, in the present application, by taking advantage of the difference in mutual solubility between the second organic small molecule (or polymer) donor and the host polymer donor material and the host non-fullerene acceptor material, the organic donor molecule with high crystallinity is used to separately regulate the aggregation state of the host donor polymer molecule and the host non-fullerene acceptor molecule in the active layer, reduce the band gap of the active layer material, and improve the short-circuit current of the device; improve the order degree of molecular arrangement in the active layer, regulate the charge transfer state of the system, reduce the energy loss of the device, and realize the synergistic improvement of the short-circuit voltage.

[0049] In summary, the present application can develop a third component of organic photovoltaic material, which provides an effective way for simultaneously reducing the band gap and open-circuit voltage loss of the active layer material of the organic solar cell device in the same system, and further breaking through the efficiency of the organic solar cell.

[0050] In a third aspect, the present application provides a solar cell, comprising an anode layer, an anode modification layer, a photoelectric active layer, a cathode modification layer and a cathode layer which are sequentially stacked.

[0051] The photoelectric active layer is the photoelectric active layer of the first aspect.

[0052] In a fourth aspect, the present application provides a preparation method of the solar cell of the third aspect, comprising the following steps:

[0053] sequentially arranging the anode modification layer, the photoelectric active layer, the cathode modification layer and the cathode layer on the surface of the anode layer to obtain the solar cell.

[0054] Compared with the prior art, the present application has the following beneficial effects:

[0055] (1) In the present application, by designing an organic conjugated small molecule donor material as a control lever, the spectral bandwidth of the light response can be widened, and by controllable adjustment of the mutual solubility between the "guest molecule" and the host donor-acceptor molecule, the aggregation state of the active material can also be changed, further reducing the band gap width of the active layer material and effectively improving the short-circuit current.

[0056] (2) In the present application, the introduction of the high-crystallinity guest material can also simultaneously improve the order degree of molecular arrangement of the active layer material, reduce the energy level disorder degree of the system and the energy loss caused thereby, thereby breaking through the limitation of the material itself on the regulation of the band gap and open-circuit voltage of the binary system, realizing the improvement of the short-circuit current while effectively improving the open-circuit voltage of the device, and further improving the energy conversion efficiency of the device. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 is the current-voltage curve of the solar device described in Example 1, Comparative Example 1 and Comparative Example 2.

[0058] Figure 2 is the curve of the open-circuit voltage of the solar device described in Example 1 as the proportion of BTID-2F is introduced.

[0059] Figure 3 is the reduction of the degree of order of the energy levels of the active layer material of the ternary system organic solar cell device achieved by introducing BTID-2F as a guest donor material into the PM6:Y6 system.

[0060] Figure 4a is the two-dimensional grazing incidence X-ray diffraction spectrum of the molecular thin film of BTID-2F with a mass ratio of 0% incorporated into PM6:Y6;

[0061] Figure 4b is the two-dimensional grazing incidence X-ray diffraction spectrum of the molecular thin film of BTID-2F with a mass ratio of 10% incorporated into PM6:Y6;

[0062] Figure 4c is the two-dimensional grazing incidence X-ray diffraction spectrum of the molecular thin film of BTID-2F with a mass ratio of 100% incorporated into PM6:Y6. DETAILED DESCRIPTION

[0063] In order to facilitate the understanding of the present application, the present application is illustrated by the following examples. It should be apparent to those skilled in the art that the examples are only to facilitate the understanding of the present application and should not be regarded as specific limitations of the present application.

[0064] Example 1

[0065] The present embodiment provides a solar cell device prepared by the following method:

[0066] (1) Take 6.4 milligrams of PM6 and add it to 1 milliliter of chloroform. Heat this solution to 60°C and stir for two hours before use;

[0067] Take 6.4 milligrams of BTID-2F and add it to 1 milliliter of chloroform. Heat this solution to 60°C and stir for two hours before use;

[0068] Take 7.6 milligrams of Y6 and add it to 1 milliliter of chloroform. Heat this solution to 40°C and stir for two hours before use;

[0069] Take 0.9 milliliters of PM6, 0.1 milliliters of BTID-2F and 1.2 milliliters of Y6 solution, and 0.005 milliliters of chloronaphthalene as liquid additive, mix the solutions and heat to 60°C and stir for two hours;

[0070] (2) The transparent conductive glass sputtered with ITO was sequentially cleaned with deionized water, acetone, and isopropanol for 15 minutes each, and then the surface of the substrate was treated with ozone. A PEDOT:PSS (poly 3,4-ethylenedioxythiophene / polystyrene sulfonate) anode modification layer about 40 nanometers thick was spin-coated and dried at 150°C for 15 minutes. The three mixed solutions prepared above were spin-coated on the PEDOT:PSS modified substrate as the photoelectric active layer under the condition of 3500 rpm / 30 seconds;

[0071] (3) Then the substrate was placed at 150°C for 15 minutes and naturally cooled. A 0.5 mg / mL concentration of PFN-Br dissolved in methanol was spin-coated onto the blended layer at a speed of 3500 rpm for 30 seconds. Finally, 2 x 10 -6 A 100 nanometer silver cathode was vacuum evaporated under a pressure of 10

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that the photoelectric active layer does not include BTID-2F, and the rest is the same as Example 1.

[0074] Comparative Example 2

[0075] The difference between this comparative example and Example 1 is that the photoelectric active layer does not include PM6, and the rest is the same as Example 1.

[0076] Performance Test

[0077] The solar cell devices described in Example 1 and Comparative Examples 1-2 and related embodiments were tested under simulated sunlight of 100 mW / m 2 The results are as follows:

[0078] (1) The open circuit voltage of the photovoltaic device based on Comparative Example 1 (PM6:Y6) was 0.846 volts, the short circuit current was 25.89 milliamperes per square centimeter, the fill factor was 75.89%, and the photoelectric conversion efficiency was 16.62%.

[0079] (2) The open circuit voltage of the photovoltaic device based on Comparative Example 2 (BTID-2F:Y6) was 0.88 volts, the short circuit current was 11.57 milliamperes per square centimeter, the fill factor was 36.48%, and the photoelectric conversion efficiency was 3.72%.

[0080] (3) The open-circuit voltage of the photovoltaic device based on Example 1 (PM6:BTID-2F:Y6 = 0.9:0.1:1.2) is 0.85 volts, the short-circuit current is 27.65 milliamperes per square centimeter, the fill factor is 76.36%, and the photoelectric conversion efficiency is 17.98%.

[0081] (4) The corresponding current-voltage curve (J-V curve) is shown in Figure 1 . In addition, with the introduction of different proportions of BTID-2F into the PM6:Y6 system, the band edge of the external quantum conversion efficiency of the device appears red shift, and when the proportion of BTID-2F is 10% by mass, the red shift is the largest (10% means that the mass ratio of BIID-2F to the donor (P-type semiconductor) material is 10%, and the rest is the same) At this time, the short-circuit current of the device is also the largest, reaching 27.65 milliamperes per square centimeter. At the same time, as shown in Figure 2 , the open-circuit voltage of the solar cell device shows a monotonic increasing trend. Through the calculation of the energy loss of the ternary organic solar cell device with different doping proportions, it is found that the introduction of BTID-2F as a guest donor material into the PM6:Y6 system realizes the reduction of the energy level disorder degree of the active layer material of the ternary system organic solar cell device (as shown in Figure 3 ), and the effective reduction of the energy loss (as shown in Table 1).

[0082] (5) Figure 4a , Figure 4b and Figure 4c are two-dimensional grazing incidence X-ray diffraction spectra of BTID-2F molecular thin films with mass ratios of 0%, 10%, and 100% incorporated into PM6:Y6, respectively.

[0083] Table 1

[0084]

[0085]

[0086] In Table 1, "8.42E-5" represents 8.42 x 10 -5 , and the rest is the same.

[0087] The applicant declares that the present application is illustrated by the above examples to explain the detailed method of the present application, but the present application is not limited to the above detailed method, that is, it does not mean that the present application must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. An optoelectrically active layer, characterized by The photoelectric active layer comprises a p-type polymer donor material, an n-type non-fullerene acceptor material, and a p-type organic conjugated small molecule donor material; The p-type organic conjugated small molecule donor material is selected from BTID-2F; The mass percentage of the p-type organic conjugated small molecule donor material is 6wt%-87wt% based on the total mass of the p-type polymer donor material and the p-type organic conjugated small molecule donor material being 100wt%.

2. The optoelectronically active layer of claim 1, wherein, The p-type polymer donor material comprises any one or a combination of at least two of PM6, PTQ10, PM7, PM7-Si, or PB-2F.

3. The optoelectronically active layer of claim 1, wherein, The n-type non-fullerene acceptor material comprises any one or a combination of at least two of Y6, a derivative of Y6, L8BO, QX1, QX2, BTP-eC9, BTP-S9, m-BTP-Phc6, BTP-4Cl, or BTP-S14.

4. A method for producing the optoelectrically active layer as claimed in any one of claims 1 to 3, characterized in that The preparation method of the photoelectric active layer comprises the following steps: The p-type polymer donor material and the p-type organic conjugated small molecule donor material are mixed, and then mixed with the n-type non-fullerene acceptor material, and then mixed with an organic solvent, and the mixed solution is coated on a substrate, dried, and the photoelectric active layer is formed.

5. The preparation method according to claim 4, characterized in that, The organic solvent is any one or a combination of at least two of chloroform, toluene, chlorobenzene, or o-dichlorobenzene.

6. The preparation method according to claim 4, characterized in that, The mixed solution further comprises an additive.

7. The production method according to claim 6, characterized by, The additive comprises any one or a combination of at least two of chloronaphthalene, 1,8-2-iodooctane, or a TPE material.

8. The preparation method according to claim 4, characterized in that, The drying temperature is 20-200℃, and the time is 0.05-48h.

9. A solar cell, characterized by, The solar cell comprises an anode layer, an anode modification layer, a photoelectric active layer, a cathode modification layer, and a cathode layer which are sequentially stacked; The photoelectric active layer is the photoelectric active layer according to any one of claims 1-3.

10. A method of producing a solar cell as claimed in claim 9, characterized in that The preparation method comprises the following steps: The anode modification layer, the photoelectric active layer, the cathode modification layer, and the cathode layer are sequentially arranged on the surface of the anode layer to obtain the solar cell.

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