Highly Efficient and Reliable Semitransparent Perovskite Solar Cells via Top Electrode Engineering

Abstract

Transparent electrodes are essential to allow optical transparency for realizing semitransparent perovskite solar cells (ST-PSCs). This study addresses gallium- and titanium-doped indium oxide (IO:GT) between the electron transport layer (ETL) and top electrode to potentially replace conventional indium tin oxide (ITO) used in inverted ST-PSCs. The shallower work function (−4.23 eV) of IO:GT than that (−4.69 eV) of conventional ITO contributes to suppressing the formation of the Schottky barrier and enhancing the charge transport at the ETL/cathode interface. By adopting IO:GT, the ST-PSC exhibits an enhancement in power conversion efficiency (PCE) from 8.59% to 17.90% (certified 17.53%) with an average visible transmittance (AVT) of 21.9%, which is the record PCE at similar AVT among all ST-PSCs reported to date. Moreover, combining these ST-PSCs as the top cell, a four-terminal perovskite–perovskite tandem solar cell is realized, showing a high PCE of 23.35%. Furthermore, the stability of the ST-PSCs is confirmed excellent, maintaining over 96% of the initial PCE after 1864 h (≈77 days) in air ambient without encapsulation, which is better than the device employing a metal cathode. Therefore, these results demonstrate that the adoption of IO:GT can be a promising route for efficient and stable inverted ST-PSCs with preferred transparency. © 2022 Wiley-VCH GmbH.