Two-dimensional lead-free iodide-based hybrid double perovskites: crystal growth, thin-film preparation and photocurrent responses

Abstract

Organometal halide perovskites (OHPs) are a kind of promising materials applied in solar cells. However, the toxicity of lead in OHPs is considered as an environmental problem. Herein, we report two lead-free two-dimensional (2D) iodide-based OHPs, namely (C₆H₁₆N₂)₂AgBiI₈·H₂O (AgBiI) and (C₆H₁₆N₂)₂CuBiI₈·0.5H₂O (CuBiI), where C₆H₁₄N₂ = 1,4-cyclohexanediamine, with a double perovskite structure. These two bimetallic perovskites show the optical band gaps of 1.93 eV and 1.68 eV. In addition, these 2D perovskite materials can form smooth films through a simple one-step spin-coating approach. Photocurrent measurements under xenon lamp irradiation indicate obvious photoresponses, suggesting that these semiconducting materials have the potential for application in light harvesting.