As the photovoltaic industry continues to evolve perovskite materials that are inorganic, non-toxic, and do not require a hole transport layer are particularly promising. However, such perovskite solar cells (PSCs) generally do not perform well. Therefore, we propose a gradient doped CsSnCl3 PSCs without hole transport layer (HTL) and investigate the optical and electrical properties of its absorption layer using first principles calculations. We further simulate and optimize this PSCs using SCAPS-1D software, focusing on various factors such as charge transport layer materials, perovskite layer thickness, doping concentration, and working temperature. Our comprehensive analysis also takes changes in the internal electric field and band structure in consideration. The study's results demonstrate that gradient doping creates an additional electric field, significantly improving the solar cell's photovoltaic conversion efficiency. When G=100, even with only two sublayers of gradient doping, a considerable performance boost is observed. The performance of optimized device is as follows: Voc = 1.1841 V, Jsc = 30.13298 mA/cm2, FF = 90.08 %, and PCE = 32.14 %. Compared with the initial PSC's efficiency of 13.93 %, it has significantly improved by 130.7 %. This research provides unique insights and guidance for the future design and manufacture of efficient, all-inorganic, non-toxic PSCs HTL-free.
