Zhang Zhihao, Gao Yifeng, Li Zicheng, Qiao Lu, Xiong Qiu, Deng Longhui, Zhang Zilong, Long Run, Zhou Qin, Du Yitian, Lan Zhang, Zhao Yanfei, Li Chen, Müllen Klaus, Gao Peng
CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China.
Laboratory for Advanced Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institute, Chinese Academy of Sciences, Xiamen, 361021, China.
Adv Mater. 2021 Aug;33(31):e2008405. doi: 10.1002/adma.202008405. Epub 2021 Jun 27.
As game-changers in the photovoltaic community, perovskite solar cells are making unprecedented progress while still facing grand challenges such as improving lifetime without impairing efficiency. Herein, two structurally alike polyaromatic molecules based on naphthalene-1,8-dicarboximide (NMI) and perylene-3,4-dicarboximide (PMI) with different molecular dipoles are applied to tackle this issue. Contrasting the electronically pull-pull cyanide-substituted PMI (9CN-PMI) with only Lewis-base groups, the push-pull 4-hydroxybiphenyl-substituted NMI (4OH-NMI) with both protonic and Lewis-base groups can provide better chemical passivation for both shallow- and deep-level defects. Moreover, combined theoretical and experimental studies show that the 4OH-NMI can bind more firmly with perovskite and the polyaromatic backbones create benign midgap states in the excited perovskite to suppress the damage by superoxide anions (energetic passivation). The polar and protonic nature of 4OH-NMI facilitates band alignment and regulates the viscosity of the precursor solution for thicker perovskite films with better morphology. Consequently, the 4OH-NMI-passivated perovskite films exhibit reduced grain boundaries and nearly three-times lower defect density, boosting the device efficiency to 23.7%. A more effective design of the passivator for perovskites with multi-passivation mechanisms is provided in this study.
作为光伏领域的变革者，钙钛矿太阳能电池正在取得前所未有的进展，但仍面临着诸如在不损害效率的情况下提高使用寿命等巨大挑战。在此，应用了两种基于萘-1,8-二甲酰亚胺（NMI）和苝-3,4-二甲酰亚胺（PMI）且具有不同分子偶极的结构相似的多芳族分子来解决这个问题。与仅具有路易斯碱基团的电子推拉氰基取代的PMI（9CN-PMI）相比，兼具质子和路易斯碱基团的推拉4-羟基联苯取代的NMI（4OH-NMI）能够为浅能级和深能级缺陷提供更好的化学钝化。此外，理论与实验相结合的研究表明，4OH-NMI能与钙钛矿更牢固地结合，且多芳族主链在激发态钙钛矿中产生良性的中间能隙态，以抑制超氧阴离子造成的损伤（能量钝化）。4OH-NMI的极性和质子性质有利于能带排列，并调节前驱体溶液的粘度，从而形成具有更好形貌的更厚钙钛矿薄膜。因此，经4OH-NMI钝化的钙钛矿薄膜的晶界减少，缺陷密度降低近三倍，将器件效率提高到了23.7%。本研究提供了一种针对具有多钝化机制的钙钛矿钝化剂的更有效设计。
