Gao Zhengyang, Chen Shengyi, Bai Yang, Wang Min, Liu Xiaoshuo, Yang Weijie, Li Wei, Ding Xunlei, Yao Jianxi
Department of Power Engineering, School of Energy, Power and Mechanical Engineering, North China Electric Power University, Baoding 071003, China.
Institute of Clusters and Low Dimensional Nanomaterials, School of Mathematics and Physics, North China Electric Power University, Beijing, People's Republic of China.
Phys Chem Chem Phys. 2021 May 19;23(19):11548-11556. doi: 10.1039/d1cp01000j.
The high efficiency of organic-inorganic hybrid perovskites has attracted the attention of many scholars all over the world, the chemical formula of which is ABX3, where A is an organic cation, B is a metal cation, and X is a halogen ion. In addition, the micro-mechanism behind the efficient photoelectric conversion needs more in-depth exploration. Therefore, in this work, based on time-dependent density functional theory (TD-DFT), the electron transfer mechanism from the ground state to the first singlet excited state was systematically investigated by electron and hole analysis and an inter-fragment charge transfer amount method (IFCT). In this work, we optimized and analyzed 99 different perovskite cluster configurations, where A sites are CH3NH3+ (MA+), NH2CHNH2+ (FA+), CH3CH2NH3+ (EA+), NH2CHOH+ (JA+), NH3OH+ (BA+), N(CH3)4+ (DA+), CH3CH2CH2NH3+ (KB+), CH3CH2CH2CH2NH3+ (KC+), C3N2H5+ (RA+), CH(CH3)2+ (TA+), and CH3NH(CH3)2+ (UA+), B sites are Ge2+, Sn2+ and Pb2+, and X sites are Cl-, Br- and I-. According to the analysis of a series of perovskite clusters of the hole-electron distribution, the distribution is mainly concentrated on BX, and electrons and holes are respectively distributed on B and X sites. The exciton binding energy decreases when the metal element changes from Ge to Pb and the halogen element changes from Cl to I. A radar chart including the exciton binding energy, excited energy, amount of net charge transfer, electron and hole overlap index, distance between the centroid of holes and electrons, and the hole and electron separation index was proposed to intuitively describe the electron transmission characteristics of perovskites. Based on that, a comprehensive score index was innovatively proposed to evaluate the photoelectric property of perovskites, providing foundational guidance for the design of high-efficiency organic-inorganic hybrid perovskites.
有机-无机杂化钙钛矿的高效率吸引了全球众多学者的关注，其化学式为ABX3，其中A为有机阳离子，B为金属阳离子，X为卤素离子。此外，高效光电转换背后的微观机制需要更深入的探索。因此，在本工作中，基于含时密度泛函理论（TD-DFT），通过电子和空穴分析以及碎片间电荷转移量方法（IFCT），系统地研究了从基态到第一单线态激发态的电子转移机制。在本工作中，我们优化并分析了99种不同的钙钛矿簇构型，其中A位点为CH3NH3+（MA+）、NH2CHNH2+（FA+）、CH3CH2NH3+（EA+）、NH2CHOH+（JA+）、NH3OH+（BA+）、N(CH3)4+（DA+）、CH3CH2CH2NH3+（KB+）、CH3CH2CH2CH2NH3+（KC+）、C3N2H5+（RA+）、CH(CH3)2+（TA+）和CH3NH(CH3)2+（UA+），B位点为Ge2+、Sn2+和Pb2+，X位点为Cl-、Br-和I-。根据对一系列钙钛矿簇的空穴-电子分布分析，该分布主要集中在BX上，电子和空穴分别分布在B和X位点。当金属元素从Ge变为Pb且卤素元素从Cl变为I时，激子结合能降低。提出了一种包含激子结合能、激发能、净电荷转移量、电子和空穴重叠指数、空穴和电子质心之间的距离以及空穴和电子分离指数的雷达图，以直观地描述钙钛矿的电子传输特性。在此基础上，创新性地提出了一个综合评分指标来评估钙钛矿的光电性能，为高效有机-无机杂化钙钛矿的设计提供基础指导。
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