Effect of mobility and band structure of hole transport layer in planar heterojunction perovskite solar cells using 2D TCAD simulation

In this paper, we investigate perovskite planar heterojunction solar cells using 2D physics-based TCAD simulation. The perovskite cell is modeled as an inorganic material with physics-based parameters. A planar structure consisting of TiO ₂ as the electron transport material (ETM), CH ₃NH ₃PbI _{3 - x}Cl _x as the absorber layer, and Spiro-OmeTAD as the hole transport material (HTM) is simulated. The simulated results match published experimental results indicating the accuracy of the physics-based model. Using this model, the effect of the hole mobility and electron affinity/band gap of the hole transport layer (HTM) is investigated. The results show that in order to achieve high efficiency, the mobility of the HTM layer should exceed 10 ^{- 4}cm ²/ V s. In addition, reducing the band offset to match the valance band of the perovskite results in achieving the highest efficiency. Moreover, the results are discussed in terms of charge transport in the HTM layer and the band alignment at the HTM/perovskite interface.