Theoretical Optimization of Lateral Heterojunction Perovskite Solar Cells: A Structural Perspective

Lateral heterojunction perovskite solar cells are well-known for their high stability. However, their efficiency is very low compared to traditional solar cells. Hence, it is crucial to theoretically study lateral heterojunction perovskite solar cells to find the reason for low efficiency and improve their performance. Therefore, in this study we simulated the lateral heterojunction perovskite solar cells to find optimal sizes and doping concentrations. We used TiO2 as Electron Transport Layer (ETL) and NiOx as Hole Transport Layer (HTL) to extract charges from CH3NH3PbI3 perovskite layer. We varied the thickness, width and doping concentration of each layer. According to the obtained results, optimal thicknesses are 40 nm for ETL and HTL, and 900 nm for perovskite layer. In lateral heterojunctions, the width of each layer is one of the key parameters that can significantly influence photoelectric parameters of the solar cell. We have found that the optimal width of ETL and HTL is 1200 nm. Optimal donor and acceptor concentrations are equal to $1\times 10^{15}$ cm−3 in the n-region and $1\times 10^{16}$ cm−3 in the p-region. A lateral heterojunction solar cell with optimal size and doping concentrations achieved 29.9% efficiency, an open circuit voltage of 1.172 V, a short circuit current of 18.33 mA/cm2 and a fill factor of 88.06%.