TEOS modification for improved performance in perovskite solar cells: addressing the interface defects and charge transfer issues of SnO₂ ETL

The remarkable advancements in performance and rapid progress of perovskite solar cells (PSCs) in recent years have captured the interest of the photovoltaics (PVs) community. Nevertheless, defects occurring at the interface between the electron transporting layer (ETL) and perovskite, along with issues related to charge transfer, significantly impede the PV efficiency of these cells. In this study, we investigated the impact of tetraethyl orthosilicate (TEOS) on charge transfer and defect states at the interface by incorporating varying concentrations of TEOS into the SnO₂ETL and modifying the interface between the ETL and perovskite. This process can passivate the defects at the ETL/perovskite (Cs_0.05(FA_0.85MA_0.15)_0.95Pb(I_0.85Br_0.15)₃) interface and significantly extend the carrier lifetime. Moreover, TEOS modification plays a promising role in the growth kinetics of the perovskite films. As a result, a power conversion efficiency (PCE) of 20.0% was achieved with admissible phase stability in the presence of TEOS as dopant in SnO₂ETL, while only 17.64% PCE was obtained for TEOS-free control structure. A promising PCE of 19.93% was achieved for ETL/TEOS/perovskite interface modification. This study presents a promising solution to address interface defects and charge transfer issues, which represent significant obstacles to the commercial scalability of PSCs.