适用于光伏的新型窄带隙二维双钙钛矿光电性能的第一性原理研究

First-principles Study of A Novel Two-dimensional Double Perovskites Solar Absorbers with Narrow Bandgap for Solar Cell

二维Dion-Jacobson(DJ)型钙钛矿因其具有的优越的电荷输运特性和良好的稳定性而受到广泛关注。然而,二维钙钛矿中铅元素的毒性问题依然制约着钙钛矿太阳能电池的大范围推广应用。提出一种新的二维钙钛矿(BDA)2 AuBiI8,其用一个一价金属Au+和一个三价金属Bi3+取代两个二价金属Pb2+,以获得无铅二维双钙钛矿材料。第一性原理计算证明:二维钙钛矿(BDA)2AuBiI8不仅具有优异的热力学稳定性,而且具有1.54 eV的直接带隙,适合太阳能电池,理论光谱极限最大效率超过30%。发现层间相互作用对能带边缘位置的确定起着重要作用。研究结果表明,DJ型结构和双取代为高效太阳能电池无铅钙钛矿的设计提供了新的方案。

2D Dion-Jacobson(DJ)perovskites have recently drawn much attention due to their superior charge trans⁃port and high environmental stability.Unfortunately,the issue of toxicity regarding Pb element in perovskites have yet to be solved.Herein,we propose a new(BDA)2AuBiI8(1,4-butanediamine)2D perovskite by substituting two Pb2+with the pair of Au+and Bi3+in order to achieve Pb-free halide perovskites.The first-principles calculations demonstrated the thermodynamic and dynamic stabilities of 2D(BDA)2AuBiI8.Furthermore,the results indicate that this new material has direct band-gap of 1.58 eV suitable for solar cells with a theoretical maximal efficiency over 30%,and allows direct transitions between band edges contrary to its bulk counterpart.The interlayer interac⁃tion of apical I-I is found playing crucial role in determining the band edges.The findings indicate DJ structure type and double substitution together provide a new method for designing lead free perovskites for efficient solar cells.