Four‐Terminal Perovskite–CdSeTe Tandem Solar Cells: From 25% toward 30% Power Conversion Efficiency and Beyond

Thin‐film tandem photovoltaic (PV) technology has emerged as a promising avenue to enhance power conversion efficiency beyond the radiative efficiency limit of single‐junction devices. Combining a tunable wide‐bandgap perovskite cell with a commercially established narrow‐bandgap cadmium selenium telluride (CdSeTe) cell in a comparatively easy‐to‐fabricate four‐terminal (4‐T) arrangement is a great step in that direction. Herein, the impact of the transparent back contact and the perovskite absorber bandgap on the performance of 4‐T perovskite–CdSeTe tandem solar cells is investigated. 4‐T perovskite–CdSeTe tandem device architecture with ≈25% efficiency is demonstrated and a feasible pathway is shown to improve the tandem efficiency to more than 30%. The results show that the integration of CdSeTe with perovskite in 4‐T tandem PV configurations represents a significant advancement toward achieving higher efficiency and low‐cost tandem PVs.