Low lead inorganic Zn-based mixed-halide perovskites CsPb0.625Zn0.375I3−β X β (X = Cl or Br) for energy generation with 23.5% efficiency

Abstract

Hybrid perovskite (HP) solar cells have garnered significant attention in recent years for their excellent light absorption, long carrier lifetime, and high diffusion length, resulting in high power conversion efficiency and superior optical performance compared to silicon solar cells. However, the organic component in HP solar cells is vulnerable to thermal variations and the presence of lead (Pb) poses a threat to the environment. To address these issues, this work proposes the use of all-inorganic halide perovskite (IHP) materials with low lead content as the absorber layer in four different perovskite solar cell configurations: CsPb0.625Zn0.375I2Br, CsPb0.625Zn0.375IBr2, CsPb0.625Zn0.375I2Cl, CsPb0.625Zn0.375ICl2. In addition, owing to the consideration novel IHP materials, it is important to identify the appropriate properties of transport layers since conventional transport layers are best suited to conventional organic–inorganic halide perovskites and may not work well with proposed IHP. Therefore, the appropriate electron transport layer (ETL) has also been investigated through optimization of electron affinity (4.0 eV − 4.23 eV), mobility (0.004 cm2/Vs to 4 cm2/Vs), and donor doping density (1015 cm−3 to 1018 cm−3). The device performance has been further analysed and optimized by varying the active layer thickness. The selected ETL is then combined with the absorber layers to evaluate performance. The effect of varying the thickness of the absorption layer is observed in all four device arrangements. Simulation results show that CsPb0.625Zn0.375ICl2 performed best among the mentioned absorber materials, with a power conversion efficiency of 23.5% with ETL parameters of 4.00 eV (electron affinity, χ), 4 cm2/Vs (electron mobility, μ n), 1×1018 cm−3 (donor doping density, Nd) and absorber layer thickness of 500 nm. Proposed work may open a window for the development of a new class of environment friendly and stable perovskite solar cells in future.