State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, Nanjing 210023, China.
The School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China.
Molecules. 2023 Jun 24;28(13):4976. doi: 10.3390/molecules28134976.
Defects in perovskite films are one of the main factors that affect the efficiency and stability of halide perovskite solar cells (PSCs). Uncoordinated ions (such as Pb, I) act as trap states, causing the undesirable non-radiative recombination of photogenerated carriers. The formation of Lewis acid-base adducts in perovskite directly involves the crystallization process, which can effectively passivate defects. In this work, 4-(trifluoromethyl)-1H-imidazole (THI) was introduced into the perovskite precursor solution as a passivation agent. THI is a typical amphoteric compound that exhibits a strong Lewis base property due to its lone pair electrons. It coordinates with Lewis acid Pb, leading to the reduction in defect density and increase in crystallinity of perovskite films. Finally, the power conversion efficiency (PCE) of PSC increased from 16.49% to 18.97% due to the simultaneous enhancement of open-circuit voltage (V), short circuit current density (J) and fill factor (FF). After 30 days of storage, the PCE of the 0.16 THI PSC was maintained at 61.9% of its initial value, which was 44.3% for the control device. The working mechanism of THI was investigated. This work provides an attractive alternative method to passivate the defects in perovskite.
钙钛矿薄膜中的缺陷是影响卤化物钙钛矿太阳能电池（PSCs）效率和稳定性的主要因素之一。配位不匹配的离子（如 Pb、I）会作为陷阱态，导致光生载流子的非辐射复合。钙钛矿中路易斯酸碱加合物的形成直接涉及结晶过程，可有效钝化缺陷。在这项工作中，将 4-（三氟甲基）-1H-咪唑（THI）作为钝化剂引入钙钛矿前驱体溶液中。THI 是一种典型的两性化合物，由于其孤对电子，表现出很强的路易斯碱性。它与路易斯酸 Pb 配位，从而降低了钙钛矿薄膜的缺陷密度并提高了其结晶度。最终，由于开路电压（V）、短路电流密度（J）和填充因子（FF）的同时提高，PSC 的功率转换效率（PCE）从 16.49%提高到了 18.97%。经过 30 天的储存，0.16 THI PSC 的 PCE 保持在初始值的 61.9%，而对照器件为 44.3%。研究了 THI 的工作机制。这项工作为钝化钙钛矿中的缺陷提供了一种有吸引力的替代方法。
