Computational investigation of lead-free NaZn0·7Ag0.3Br3 based double-perovskite solar cell

This research work contributes to the numerical simulation of Pb-free double perovskite NaZn0·7Ag0.3 Br3-based perovskite solar cells via SCAPS 1D. For the initial simulation, TiO2 and PEDOT:PSS is considered as an initial charge transport layer with the device efficiency reaching up to 13.44 %. Further, the impact of different ETL and HTL is studied and optimized. The optimization is performed by correlating the Vbi with the VOC. There is a strong relationship is obtained between the Vbi with the VOC. It is thus revealed from the simulation that to conveniently transport electrons the ECB_ETL should lie below ECB_PVK. However, for convenient transport of holes, the EVB_HTL should lie above EVB_PVK. Using this concept, the optimized ETL and HTL obtained are ZnSe and ZnTe. Moreover, the influence of the thickness of the Pb-free double perovskite is also realized with the optimized thickness obtained as 700 nm which improves device efficiency to 27.59 % and other photovoltaic parameters as VOC = 1.59 V, JSC = 21.90 mA/cm2, FF = 78.92 % with the optimized structure as (FTO/ZnSe/NaZn0.7 Ag0·3Br3/ZnTe/Au). Thus, the proposed results reveal that the Pb-free double perovskite NaZnBr3 (NaZn0·7Ag0.3Br3) based perovskite solar cell is considered one of the most intriguing candidates for future perovskite solar cell applications. •The simulation of the Pb-Free NaZnBr3 (NaZn0.7 Ag0.3 Br3) based perovskite solar cell is performed.•The charge transport layers are optimized based on their relation between the built-in potential and the VOC.•The VB and CB position of the ETL and HTL corresponds to the perovskite absorber layer shows a significant impact on the device performance.•The ZnTe and ZnSe as a hole and electron transport layer elevates device efficiency up to 27.02 %.•After optimization, the device efficiency improves up to 27.59 % of Pb-Free NaZnBr3 (NaZn0.7 Ag0.3 Br3) perovskite solar cell.