A Hybrid Functional Study on Perovskite-Based Compounds CsPb1-alpha Zn alpha I3-beta X beta (X = Cl or Br)

Inorganic perovskites have attracted a great deal of attention because of their stability. Unfortunately, a weak optical response and the toxicity of lead are hampering their development. Motivated by these facts, we focus herein on the perovskite-based doped series CsPb1-alpha Zn alpha I3-beta X beta (X = CI or Br). The geometric structures and the electronic and optical properties of CsPb1-alpha Zn alpha I3-beta X beta (X = CI or Br) are investigated systematically by hybrid functional theory. Analysis of the electronic properties indicates that Zn/Cl/Br mono-doping and co-doping efficiently tune bandgaps. Moreover, we find that the ability to obtain electrons for CsPb0.625Zn0.375I2Cl is superior to the abilities of the others, which implies a stronger electron transition. In addition, CsPb0.625Zn0.375I2Cl and CsPb0.623Zn0.373I2Br show stronger visible-light responses in the range of 467-780 nm. Both CsPb0.625Zn0.375I2Cl and CsPb0.623Zn0.373I2Br Br are hence good choices for photovoltaic applications. Furthermore, the physically accessible region is also explored herein. These findings shed new light on the design of highly efficient and low-lead perovskite-based optoelectronic materials.