Figure 5. 2D-GIWAXS patterns of a) PBDB-T, b) BZO-4Cl, c) PBDB-T: BZO-4Cl, d) PBDB-T: BZ4F-O-1 and e) PBDB-T: BZ4F-O-1: BZO-4Cl films; f) In-plane (dashed) and out-of-plane (solid) GIWAXS curves of the corresponding 2D patterns.
Conclusions
In conclusion, we employ a synergetic alkoxy side-chain and chlorine-contained end group strategy for ultra-NBG heptacyclic SMAs. And two A-DA’D-A type ultra-NBG acceptors, BZO-4F and BZO-4Cl are designed and synthesized with theE gopt of 1.29 eV and 1.25 eV, respectively. By blending with the polymer donor PBDB-T, the BZO-4Cl-based device shows a moderate PCE of 12.48% with aJ SC of 26.86 mA cm-2, which is slightly higher than that of the BZO-4F-based device. However, the photovoltaic performance is limited by the lowV OC and FF. BZ4F-O-1 with a high LUMO level and a complementary absorption is considered to be introduced into the PBDB-T: BZO-4Cl system to construct ternary OSCs. As well investigated, the ternary blend materials possess good miscibility. Besides, the recombination process of the ternary device is suppressed and the charge transport is significantly improved. Furthermore, the molecular π-π stacking is also subtly controlled, leading to an optimal blend morphology. Consequently, the PBDB-T: BZ4F-O-1: BZO-4Cl-based ternary device achieves a high PCE of 15.51% with the simultaneously increasedV OC (0.77 V), J SC (27.85 mA cm-2) and FF (0.71). This work highlights a molecular strategy of altering the oxygen position along the side chains and chlorine-substitution for ultra-NBG acceptor, which is a potential alternative in semi-transparent OSCs.
Experimental
Synthesis of BZO-4F andBZO-4Cl: Under argon, compound 9 (0.14 g,0.12 mmol) and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (0.11 g, 0.48 mmol) were dissolved in chloroform (30 mL). Pyridine (1.5 mL) was added. After stirring at 65 oC overnight, the mixture was cooled to room temperature, the solution was concentrated under reduced pressure, and poured into methanol and filtered. The residue was purified in a silica gel column using petroleum ether/dichloromethane (1:1, v/v) as the eluent. BZO-4F was obtained as a dark blue solid (135 mg, 70% yield). BZO-4Cl was synthesized by the same method of BZO-4F.
Device fabrication: The optimized photovoltaic devices were fabricated with a conventional structure of Glass/ITO/PEDOT: PSS/ PBDB-T: acceptor/PDINN/Ag. Pre-patterned ITO coated glass substrates (Advanced Election Technology Co., Ltd) were washed with deionized water and isopropyl alcohol in an ultrasonic bath for 15 minutes. After blow-drying by high-purity nitrogen, all ITO substrates are cleaned in the ultraviolet ozone cleaning system for 20 minutes. Subsequently, a thin layer of PEDOT: PSS (Xi’an Polymer Light Technology Corp 4083) was deposited through spin-coating on pre-cleaned ITO-coated glass at 4500 rpm for 30 s and dried subsequently at 150°C for 15 minutes in atmospheric air. Then the photovoltaic layers were spin-coated in a glovebox from a solution of PBDB-T: acceptors (14.5mg/mL with 0.1vol% CN with the PBDB-T: acceptors weight ratios of 1:1.2, PBDB-T: BZ4F-O-1: BZO-4Cl = 1: 0.6: 0.6) in CF. The optimal active layers were fabricated by spin-coating at about 3000 rpm for the 30s. Then the blend films were treated with thermal annealing at 100 oC for 10 min. After cooling to room temperature, a PDINN layer via a solution concentration of 1 mg/mL was deposited at the top of the active layer at a rate of 3000 rpm for 30 s. Finally, the top Ag electrode of 100 nm thickness was thermally evaporated through a mask onto the cathode buffer layer under a vacuum of 1.5×10-4 Pa.
Supporting Information
The supporting information for this article is available on the WWW under https://doi.org/10.1002/cjoc.2021xxxxx.
Acknowledgement
This work was supported by National Natural Science Foundation of China (52125306, 22005347).
Author contributions
Yingping Zou and Qingya Wei conceived the idea and designed the acceptors. Qingya Wei synthesized the acceptor materials and tested the molecular optoelectronic properties. Songting Liang fabricated the organic solar cells and characterized the photovoltaic parameters. Qingya Wei and Songting Liang tested the AFM and TEM. BeiBei Qiu helped the theoretical calculations. Xinhui Lu and Yuang Fu supported the GIWAXS. Qingya Wei wrote the original draft, and all the authors including Jun Yuan, Wei Liu and Xiang Xu contributed to the data analysis and manuscript revision. Yingping Zou directed this project.
References
[1] Lin, Y. Z.; Wang, J. Y.; Zhang, Z. G.; Bai, H. T.; Li, Y. F.; Zhu, D. B.; Zhan, X. W., An Electron Acceptor Challenging Fullerenes for Efficient Polymer Solar Cells. Adv. Mater. 2015,27 , 1170-1174.
[2] Yuan, J.; Zhang, Y.; Zhou, L.; Zhang, G.; Yip, H.-L.; Lau, T.-K.; Lu, X.; Zhu, C.; Peng, H.; Johnson, P. A.; Leclerc, M.; Cao, Y.; Ulanski, J.; Li, Y.; Zou, Y., Single-Junction Organic Solar Cell with over 15% Efficiency Using Fused-Ring Acceptor with Electron-Deficient Core. Joule 2019, 3 , 1140-1151.
[3] Wei, Q. Y.; Liu, W.; Leclerc, M.; Yuan, J.; Chen, H. G.; Zou, Y. P., A-DA’D-A non-fullerene acceptors for high-performance organic solar cells. Sci. China-Chem. 2020, 63 , 1352-1366.
[4] Zheng, Z.; Yao, H.; Ye, L.; Xu, Y.; Zhang, S.; Hou, J., PBDB-T and its derivatives: A family of polymer donors enables over 17% efficiency in organic photovoltaics. Mater. Today 2020,35 , 115-130.
[5] Bi, P. Q.; Zhang, S. Q.; Wang, J. W.; Ren, J. Z.; Hou, J. H., Progress in Organic Solar Cells: Materials, Physics and Device Engineering. Chin. J. Chem. 2021, 39 , 2607-2625.
[6] He, K.; Kumar, P.; Yuan, Y.; Li, Y., Wide bandgap polymer donors for high efficiency non-fullerene acceptor based organic solar cells.Mater. Adv. 2021, 2 , 115-145.
[7] Wei, Q.; Yuan, J.; Yi, Y.; Zhang, C.; Zou, Y., Y6 and its derivatives: molecular design and physical mechanism. Natl. Sci. Rev. 2021, 8 , nwab121.
[8] Zhang, Z. G.; Li, Y., Polymerized Small-Molecule Acceptors for High-Performance All-Polymer Solar Cells. Angew Chem. Int. Ed.2021, 60 , 4422-4433.
[9] Yuan, J.; Zhang, C.; Qiu, B.; Liu, W.; So, S. K.; Mainville, M.; Leclerc, M.; Shoaee, S.; Neher, D.; Zou, Y., Effects of energetic disorder in bulk heterojunction organic solar cells. Energy Environ. Sci. 2022, 15 , 2806-2818.
[10] Yuan, J.; Zou, Y., The history and development of Y6.Org. Electron. 2022, 102 , 106436.
[11] Wang, X. D.; Zeng, R.; Lu, H.; Ran, G. L.; Zhang, A. D.; Chen, Y. N.; Liu, Y. H.; Liu, F.; Zhang, W. K.; Tang, Z.; Bo, Z. S., A Simple Nonfused Ring Electron Acceptor with a Power Conversion Efficiency Over 16%. Chin. J. Chem. 2023, 41 , 665-671.
[12] Feng, L.; Yuan, J.; Zhang, Z.; Peng, H.; Zhang, Z.-G.; Xu, S.; Liu, Y.; Li, Y.; Zou, Y., Thieno[3,2-b]pyrrolo-Fused Pentacyclic Benzotriazole-Based Acceptor for Efficient Organic Photovoltaics.ACS Appl. Mater. Interfaces 2017, 9 , 31985-31992.
[13] Jiang, K.; Wei, Q.; Lai, J. Y. L.; Peng, Z.; Kim, H. K.; Yuan, J.; Ye, L.; Ade, H.; Zou, Y.; Yan, H., Alkyl Chain Tuning of Small Molecule Acceptors for Efficient Organic Solar Cells. Joule2019, 3 , 3020-3033.
[14] Cai, F.; Zhu, C.; Yuan, J.; Li, Z.; Meng, L.; Liu, W.; Peng, H.; Jiang, L.; Li, Y.; Zou, Y., Efficient organic solar cells based on a new ”Y-series” non-fullerene acceptor with an asymmetric electron-deficient-core. Chem. Commun. 2020, 56 , 4340-4343.
[15] Cui, Y.; Yao, H.; Zhang, J.; Xian, K.; Zhang, T.; Hong, L.; Wang, Y.; Xu, Y.; Ma, K.; An, C.; He, C.; Wei, Z.; Gao, F.; Hou, J., Single-Junction Organic Photovoltaic Cells with Approaching 18% Efficiency. Adv. Mater. 2020, 32 , e1908205.
[16] Gao, W.; Fu, H.; Li, Y.; Lin, F.; Sun, R.; Wu, Z.; Wu, X.; Zhong, C.; Min, J.; Luo, J.; Woo, H. Y.; Zhu, Z.; Jen, A. K. Y., Asymmetric Acceptors Enabling Organic Solar Cells to Achieve an over 17% Efficiency: Conformation Effects on Regulating Molecular Properties and Suppressing Nonradiative Energy Loss. Adv. Energy Mater.2020, 11 , 2003177.
[17] Lai, H.; Zhao, Q.; Chen, Z.; Chen, H.; Chao, P.; Zhu, Y.; Lang, Y.; Zhen, N.; Mo, D.; Zhang, Y.; He, F., Trifluoromethylation Enables a 3D Interpenetrated Low-Band-Gap Acceptor for Efficient Organic Solar Cells. Joule 2020, 4 , 688-700.
[18] Li, S.; Zhan, L.; Jin, Y.; Zhou, G.; Lau, T. K.; Qin, R.; Shi, M.; Li, C. Z.; Zhu, H.; Lu, X.; Zhang, F.; Chen, H., Asymmetric Electron Acceptors for High‐Efficiency and Low‐Energy‐Loss Organic Photovoltaics.Adv. Mater. 2020, 32 , 2001160.
[19] Zhang, Z.; Li, Y.; Cai, G.; Zhang, Y.; Lu, X.; Lin, Y., Selenium Heterocyclic Electron Acceptor with Small Urbach Energy for As-Cast High-Performance Organic Solar Cells. J. Am. Chem. Soc.2020, 142 , 18741-18745.
[20] Li, C.; Zhou, J.; Song, J.; Xu, J.; Zhang, H.; Zhang, X.; Guo, J.; Zhu, L.; Wei, D.; Han, G.; Min, J.; Zhang, Y.; Xie, Z.; Yi, Y.; Yan, H.; Gao, F.; Liu, F.; Sun, Y., Non-fullerene acceptors with branched side chains and improved molecular packing to exceed 18% efficiency in organic solar cells. Nat. Energy 2021, 6 , 605-613.
[21] Wang, Y.; Fan, Q. P.; Wang, Y. L.; Fang, J.; Liu, Q.; Zhu, L.; Qiu, J. J.; Guo, X.; Liu, F.; Su, W. Y.; Zhang, M. J., Modulating Crystallinity and Miscibility via Side-chain Variation Enable High Performance All-Small-Molecule Organic Solar Cells. Chin. J. Chem. 2021, 39 , 2147-2153.
[22] Gao, W.; Qi, F.; Peng, Z.; Lin, F. R.; Jiang, K.; Zhong, C.; Kaminsky, W.; Guan, Z.; Lee, C. S.; Marks, T. J.; Ade, H.; Jen, A. K., Achieving 19% Power Conversion Efficiency in Planar-Mixed Heterojunction Organic Solar Cells Using a Pseudosymmetric Electron Acceptor. Adv. Mater. 2022, 34 , e2202089.
[23] Kong, X.; Zhu, C.; Zhang, J.; Meng, L.; Qin, S.; Zhang, J.; Li, J.; Wei, Z.; Li, Y., The effect of alkyl substitution position of thienyl outer side chains on photovoltaic performance of A–DA′D–A type acceptors. Energy Environ. Sci. 2022, 15 , 2011-2020.
[24] Liang, Y.; Zhang, D.; Wu, Z.; Jia, T.; Lüer, L.; Tang, H.; Hong, L.; Zhang, J.; Zhang, K.; Brabec, C. J.; Li, N.; Huang, F., Organic solar cells using oligomer acceptors for improved stability and efficiency. Nat. Energy 2022, 7 , 1180-1190.
[25] Liu, W.; Yuan, J.; Zhu, C.; Wei, Q.; Liang, S.; Zhang, H.; Zheng, G.; Hu, Y.; Meng, L.; Gao, F.; Li, Y.; Zou, Y., A-π-A structured non-fullerene acceptors for stable organic solar cells with efficiency over 17%. Sci. China Chem. 2022, 65 , 1374-1382.
[26] Wang, H.; Cao, C.; Chen, H.; Lai, H.; Ke, C.; Zhu, Y.; Li, H.; He, F., Oligomeric Acceptor: A ”Two-in-One” Strategy to Bridge Small Molecules and Polymers for Stable Solar Devices. Angew Chem. Int. Ed. 2022, 61 , e202201844.
[27] Zhang, L.; Zhang, Z.; Deng, D.; Zhou, H.; Zhang, J.; Wei, Z., ”N-pi-N” Type Oligomeric Acceptor Achieves an OPV Efficiency of 18.19% with Low Energy Loss and Excellent Stability. Adv. Sci.2022, 9 , e2202513.
[28] Zheng, Z.; Wang, J.; Bi, P.; Ren, J.; Wang, Y.; Yang, Y.; Liu, X.; Zhang, S.; Hou, J., Tandem Organic Solar Cell with 20.2% Efficiency. Joule 2022, 6 , 171-184.
[29] Zhu, L.; Zhang, M.; Xu, J.; Li, C.; Yan, J.; Zhou, G.; Zhong, W.; Hao, T.; Song, J.; Xue, X.; Zhou, Z.; Zeng, R.; Zhu, H.; Chen, C. C.; MacKenzie, R. C. I.; Zou, Y.; Nelson, J.; Zhang, Y.; Sun, Y.; Liu, F., Single-junction organic solar cells with over 19% efficiency enabled by a refined double-fibril network morphology. Nat. Mater. 2022, 21 , 656-663.
[30] Wang, Y.; Zheng, Z.; Wang, J.; Liu, X.; Ren, J.; An, C.; Zhang, S.; Hou, J., New Method for Preparing ZnO Layer for Efficient and Stable Organic Solar Cells. Adv. Mater. 2023, 35 , e2208305.
[31] He, C.; Li, Y.; Liu, Y.; Li, Y.; Zhou, G.; Li, S.; Zhu, H.; Lu, X.; Zhang, F.; Li, C.-Z.; Chen, H., Near infrared electron acceptors with a photoresponse beyond 1000 nm for highly efficient organic solar cells. J. Mater. Chem. A 2020, 8 , 18154-18161.
[32] Qi, F.; Jiang, K.; Lin, F.; Wu, Z.; Zhang, H.; Gao, W.; Li, Y.; Cai, Z.; Woo, H. Y.; Zhu, Z.; Jen, A. K. Y., Over 17% Efficiency Binary Organic Solar Cells with Photoresponses Reaching 1000 nm Enabled by Selenophene-Fused Nonfullerene Acceptors. ACS Energy Lett.2020, 6 , 9-15.
[33] Jia, Z.; Qin, S.; Meng, L.; Ma, Q.; Angunawela, I.; Zhang, J.; Li, X.; He, Y.; Lai, W.; Li, N.; Ade, H.; Brabec, C. J.; Li, Y., High performance tandem organic solar cells via a strongly infrared-absorbing narrow bandgap acceptor. Nat. Commun. 2021, 12 , 178.
[34] Liu, W.; Sun, S.; Xu, S.; Zhang, H.; Zheng, Y.; Wei, Z.; Zhu, X., Theory-Guided Material Design Enabling High-Performance Multifunctional Semitransparent Organic Photovoltaics without Optical Modulations. Adv. Mater. 2022, 34 , e2200337.
[35] Qi, F.; Jones, L. O.; Jiang, K.; Jang, S. H.; Kaminsky, W.; Oh, J.; Zhang, H.; Cai, Z.; Yang, C.; Kohlstedt, K. L.; Schatz, G. C.; Lin, F. R.; Marks, T. J.; Jen, A. K., Regiospecific N-alkyl substitution tunes the molecular packing of high-performance non-fullerene acceptors.Mater. Horiz. 2022, 9 , 403-410.
[36] Song, Y.; Zhong, Z.; Li, L.; Liu, X.; Huang, J.; Wu, H.; Li, M.; Lu, Z.; Yu, J.; Hai, J., Fused-heterocycle engineering on asymmetric non-fullerene acceptors enables organic solar cells approaching 29 mA/cm2 short-circuit current density. Chem. Eng. J.2022, 430 , 132830.
[37] Zhao, W.; Li, S.; Yao, H.; Zhang, S.; Zhang, Y.; Yang, B.; Hou, J., Molecular Optimization Enables over 13% Efficiency in Organic Solar Cells. J. Am. Chem. Soc. 2017, 139 , 7148-7151.
[38] Dai, S.; Li, T.; Wang, W.; Xiao, Y.; Lau, T. K.; Li, Z.; Liu, K.; Lu, X.; Zhan, X., Enhancing the Performance of Polymer Solar Cells via Core Engineering of NIR-Absorbing Electron Acceptors. Adv. Mater. 2018, 30 , e1706571.
[39] Dai, S.; Xiao, Y.; Xue, P.; James Rech, J.; Liu, K.; Li, Z.; Lu, X.; You, W.; Zhan, X., Effect of Core Size on Performance of Fused-Ring Electron Acceptors. Chem. Mater. 2018,30 , 5390-5396.
[40] Zhang, C.; Yuan, J.; Ho, J. K. W.; Song, J.; Zhong, H.; Xiao, Y.; Liu, W.; Lu, X.; Zou, Y.; So, S. K., Correlating the Molecular Structure of A‐DA′D‐A Type Non‐Fullerene Acceptors to Its Heat Transfer and Charge Transport Properties in Organic Solar Cells. Adv. Funct. Mater. 2021, 31 , 2101627.
[41] Lei, T.; Wang, J.-Y.; Pei, J., Roles of Flexible Chains in Organic Semiconducting Materials. Chem. Mater. 2013,26 , 594-603.
[42] Li, J. Y.; Li, H.; Ma, L. J.; Zhang, S. Q.; Hou, J. H., Design and Synthesis of N-Alkylaniline-Substituted Low Band-Gap Electron Acceptors for Photovoltaic Application. Chin. J. Chem.2023, 41 , 424-430.
[43] Chen, H.-Y.; Hou, J.; Zhang, S.; Liang, Y.; Yang, G.; Yang, Y.; Yu, L.; Wu, Y.; Li, G., Polymer solar cells with enhanced open-circuit voltage and efficiency. Nat. Photon. 2009, 3 , 649-653.
[44] Cui, C.; Wong, W.-Y.; Li, Y., Improvement of open-circuit voltage and photovoltaic properties of 2D-conjugated polymers by alkylthio substitution. Energy Environ. Sci. 2014,7 , 2276-2284.
[45] Cui, C.; He, Z.; Wu, Y.; Cheng, X.; Wu, H.; Li, Y.; Cao, Y.; Wong, W.-Y., High-performance polymer solar cells based on a 2D-conjugated polymer with an alkylthio side-chain. Energy Environm. Sci. 2016, 9 , 885-891.
[46] Cheung, A. M. H.; Yu, H.; Luo, S.; Wang, Z.; Qi, Z.; Zhou, W.; Arunagiri, L.; Chang, Y.; Yao, H.; Ade, H.; Yan, H., Incorporation of alkylthio side chains on benzothiadiazole-based non-fullerene acceptors enables high-performance organic solar cells with over 16% efficiency.J. Mater. Chem. A 2020, 8 , 23239-23247.
[47] Chen, Y. Z.; Bai, F. J.; Peng, Z. X.; Zhu, L.; Zhang, J. Q.; Zou, X. H.; Qin, Y. P.; Kim, H.; Yuan, J.; Ma, L. K.; Zhang, J.; Yu, H.; Chow, P. C. Y.; Huang, F.; Zou, Y. P.; Ade, H.; Liu, F.; Yan, H., Asymmetric Alkoxy and Alkyl Substitution on Nonfullerene Acceptors Enabling High-Performance Organic Solar Cells. Adv. Energy Mater.2021, 11 , 2003141.
[48] Wei, Q.; Liang, S.; Liu, W.; Hu, Y.; Qiu, B.; Ren, J.; Yuan, J.; Huang, F.; Zou, Y.; Li, Y., Effects of Oxygen Position in the Alkoxy Substituents on the Photovoltaic Performance of A-DA′D-A Type Pentacyclic Small Molecule Acceptors. ACS Energy Lett.2022, 7 , 2373-2381.
[49] Liu, S.; Yuan, J.; Deng, W.; Luo, M.; Xie, Y.; Liang, Q.; Zou, Y.; He, Z.; Wu, H.; Cao, Y., High-efficiency organic solar cells with low non-radiative recombination loss and low energetic disorder.Nat. Photon. 2020, 14 , 300-305.
[50] Yao, J.; Qiu, B.; Zhang, Z. G.; Xue, L.; Wang, R.; Zhang, C.; Chen, S.; Zhou, Q.; Sun, C.; Yang, C.; Xiao, M.; Meng, L.; Li, Y., Cathode engineering with perylene-diimide interlayer enabling over 17% efficiency single-junction organic solar cells. Nat. Commun.2020, 11 , 2726.
[51] Li, J.; Zhang, C.; Zhong, X.; Deng, W.; Hu, H.; Wang, K., End-Group Engineering of Chlorine-Trialkylsiylthienyl Chain-Substituted Small-Molecule Donors for High-Efficiency Ternary Solar Cells.Small 2022 , e2205572.