通过分子设计精准控制体异质结（BHJ）形貌是开发高性能有机太阳能电池（OSCs）面临的长期挑战之一。
近日，武汉大学闵杰教授和孙瑞副研究员等人在Science China Materials发表研究论文，设计并合成了三种具有不同侧链（分别在苯并三唑单元上引入甲基、2-乙基己基和2-癸基十四烷基）的小分子受体（SMAs），即R-M、R-EH和R-DTD。
本文要点
1) 这种侧链调控可以有效调节受体/受体（A/A）和给体/受体（D/A）分子之间的相互作用，从而实现BHJ活性层结构的微调。2) 与R-M和R-DTD相比，R-EH与给体PM6表现出更强的A/A和D/A相互作用，形成更紧密的分子排列，改善了BHJ网络结构，增强了电荷传输和提取性能。3) 在三个体系中，PM6:R-EH不仅表现出超过18%的器件效率，还表现出优异的稳定性。本研究深化了A/A和D/A相互作用对BHJ形貌的协同调节作用，为实现高效且稳定的工业化OSCs提供了新的思路。Figure 1. (a) Molecular structures of the investigated photovoltaic materials. (b) Normalized absorption spectra of the SMA materials in dilute CF solution (dash-dot lines) and the thin films (solid lines). (c) Energy level diagram of PM6 and SMAs. (d) DSC curves of acceptors with a heating rate of 10 °C min−1 under a nitrogen atmosphere. (e) Scattering profiles of OOP for the investigated SMAs. (f) Histograms of CCL, ΔHm, and μe for the investigated SMAs.Figure 2. (a) Water and (b) ethylene glycol contact angles measured on surfaces of the neat films. (c) Surface energy of the neat films and Flory-Huggins interaction parameter (χ) values of the relevant systems based on PM6 as the donor. (d–f) The GIWAXS patterns for blend films of PM6:R-M, PM6:R-EH, and PM6:R-DTD. (g) Scattering profiles for blend films of PM6:R-M, PM6:R-EH and PM6:R-DTD. (h) Histograms of CCL, μh, μe, and μh/μh of the investigated blend films.![]()
Figure 3. (a) Illustrations of device structures and A/A and D/A interactions of SMAs. (b) J-V characteristics of the best OSCs under the illumination of AM 1.5G, 100 mW cm−2. (c) The corresponding EQE spectra of devices. (d) Characteristics of the photocurrent density versus effective voltage (Jph-Veff). (e) PL spectra of the pristine acceptors (R-M, R-EH, R-DTD) and the corresponding blend films (excited at 532 nm). (f) Measurement of VOC versus light intensity for the devices. (g) Normalized TPV data for the relevant solar cells.![]()
Figure 4. Light stability behaviors of the corresponding OSCs with MPP tracking under one sun illumination. (a) Normalized PCE, VOC, FF, and JSC for different acceptors (R-M, R-EH, and R-DTD)-based OSCs. (b) OOP direction of GIWAXS line cuts for fresh and aged blend films based on SMAs. (c) Histograms of CCL and KCCL for fresh and aged blend films based on SMAs. (d) Histograms of the charge extraction time before and after light aging. (e) Histograms of the carrier mobility before and after light aging.Jiangtong Zhao, Xinrong Yang, Yiming Shao, Rui Sun, Jie Min. Simultaneously improving efficiency and stability of organic solar cells by enhancing molecular crystallinity and intermolecular interactions. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-3074-6
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