Halogen substitution assisted modification on phase transition point and band gap of (DBU) PbX3 (X = Cl, Br, I)

Abstract

Lead halide hybrid perovskite with typical formula ABX3 has great application prospects in the field of optoelectronic devices due to their excellent characteristics, including easy processing, adjustable structure, tunable band gaps. In this work, we report three halogen-substituted lead halide hybrid perovskites, namely, (DBU) PbX3 (DBU ​= ​1,8-diazabicyclo [5.4.0] undec-7-ene, X ​= ​Cl, Br, I). These hybrid compounds have similar one-dimensional chain perovskite structures and undergo above-room temperature solid to solid phase transition. The variation of the heavy halogen atoms from Cl, Br to I on the X site causes a gradually larger octahedral space, which contributes to the decrease in phase transition temperature, because of the confinement effect. Meanwhile, a reduction in the band gap occurs for (DBU) PbX3 was obtained. This work highlights the halogen substitution on the lead halide hybrid perovskite towards excellent performance, which will benefit the field of optoelectronics.