Insights on the opto-electronic structure of the inorganic mixed halide perovskites γ-CsPb(I_1-xBr_x)₃ with low symmetry black phase

Inorganic halide perovskites especially CsPbI₃ have attracted great attention in optoelectronics and photovoltaic fields due to their good thermal stability and comparable efficiency with organometallic perovskites. CsPbI₃ has two main phases, active black phase at high temperature and inactive yellow phase at low temperature. To obtain the perovskite phase, thin films should be heated above 320 °C, this high temperature can damage the flexible substrates. Recently, it has been suggested that partial or total substitution of iodide by bromide such as CsPbI_3−xBr_x, could stabilize the preferred perovskite black phase at lower temperature. Hence, it was very necessary to investigate the electronic and optical characteristics of these materials. The structural, electronic, some carrier transport and optical properties of all-inorganic cesium lead mixed halide perovskite with a low symmetry orthorhombic structure were methodically investigated using density functional theory.