Highly conducting Al-doped zinc oxide electron transport layer for all-inorganic perovskite solar cells: An experimental and simulation study

The need for an excellent electron transport layer (ETL) material is immensely significant for higher conversion efficiency of perovskite solar cells (PSCs). This work centers on the exceptional performance achieved by the Al-doped ZnO (AZO) ETL with reference to undoped ZnO (ZnO). Both doped and undoped ETL materials were synthesized and characterized to determine their structural, morphological, and optical behavior. In this work, solar cell performance of two similar CsPbIBr₂-based PSCs with different ETLs namely FTO/ZnO/CsPbIBr₂/NiO (Cell #1) and FTO/AZO/CsPbIBr₂/NiO (Cell #2) are investigated through numerical simulation method. The obtained characteristics affirms that Cell #2 offers sufficient better performance parameters (J_sc, V_oc, FF, and η) against Cell #1 with respect to variation in CsPbIBr₂ PVT, ETL and HTL thickness. The adverse effect on J-V characteristics caused by controllable introduction of defect density (N_t) in PVT layer is negligible for Cell #2 compared to its ZnO counterpart. Further, the contribution of AZO ETL layer on cell's performance is evaluated in terms of variation in respective ETL and HTL thickness. The investigation reveals that Cell #2 offers a desirable η of 19.46% at electron capture cross section of 2 × 10⁻¹⁵ cm² while Cell #1 delivers only 12.48%.