Perovskite solar cells: investigation of structural, optical and device performance analysis of Al–Sn co-doped ZnO electron transport layer

Synthesis of undoped and Aluminum (Al)—Tin (Sn) (2 & 4 wt%) co-doped Zinc Oxide (ZnO) Nanoparticles (NPs) is achieved by co-precipitation technique. PXRD pattern exposes the hexagonal crystal structure of ZnO NPs without any impurity. Optical bandgap was modified as 3.26, 3.28 and 3.30 eV respectively for undoped and 2 & 4 wt% of Al-Sn co-doped ZnO NPs. The light absorbance and bandgap position was improved by introducing the Al-Sn (2 & 4 wt%) as co-dopants. This can enhance the bandgap position of ZnO which reduces the energy barrier in the electron extraction. Also, impedes the interface recombination losses between ETL/perovskite. The open-circuit voltage ( V oc ) of planar PSCs consequently increases. Notably, the sample Al-Sn (2 wt%) co-doped ZnO layer exhibited a better power conversion efficiency (6.23%), compared to other layers (pure ZnO is 3.29% and 4 wt. % of Al-Sn co-doped ZnO is 4.21%). Also, it improved the co-doped ETL-based planar perovskite solar cell device open current voltage and fill factor, respectively. The fabricated P-PSC device stability analysis were studied at 250 h under one sun irradiation. Overall, the co-doped ZnO ETL successfully adjusts the optical bandgap position and enhanced the electrical conductivity of ETL. The results provide an effective strategy for fabricating high-efficiency planar perovskite solar cells.