Rigid Amine‐Induced Pseudo‐3D Lead‐Free Bismuth Halide Perovskite with an Improved Band Edge for Visible‐Light Absorption

• Published in: ChemSusChem 2020-05, Vol.13 (10), p.2753-2760
• Main Authors: Wang, Yanyan, Wen, Rui, Liu, Yuanyuan, Le‐Yu Bi, Yang, Mingming, Sun, Huaming, Yan‐Zhen Zheng, Zhang, Guofang, Gao, Ziwei
• Format: Article
• Language: English
• Subjects: Absorbers; Bismuth halides; Electromagnetic absorption; Energy gap; Optoelectronics; Parallelepipeds; Perovskites; Toxicity
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.202000282

Bismuth organometal halide perovskites have recently been investigated as potential substitutes for lead perovskite solar‐cell absorbers because of their lower toxicity. However, the narrowing of the band gap remains a crucial challenge for their practical application. All known Bi‐based perovskites have large band gaps, thereby affording weak visible‐light absorption. This study concerns a novel, lead‐free, pseudo‐3 D perovskite optoelectronic material, (MV)BiI5 (MV2+=methyl viologen). The pseudo‐3 D metal‐halogen perovskite‐like structure is constructed by connecting [BiI5] 2+ units via I⋅⋅⋅I contacts. MV, as a rigid organic amine, is located at the center of each parallelepiped to balance the charge and stabilize the structure. (MV)BiI5 has a narrow band gap of 1.48 eV and a better photoresponse than (MV)BiCl5 with a 1 D structure. (MV)BiI5 is the first Bi‐based perovskite compound with a band gap energy comparable with (CH3NH3)PbI3, which is encouraging for optoelectronic applications. This research will open a potential pathway for the design of pseudo‐3 D Bi‐based perovskites with performances comparable with APbX3 absorbers.