Enhancing the performance of hole-conductor free carbon-based perovskite solar cells through rutile-phase passivation of anatase TiO2 scaffold

Abstract Surface passivation of the electron transport layer in perovskite solar cells has been proven to be one crucial strategy to improve the power conversion efficiency. In this study, we introduce rutile phase titania shell to passivate anatase TiO 2 scaffold, forming anatase@rutile mixed-phase TiO 2 scaffold in hole-conductor-free carbon based perovskite solar cells. Anatase@rutile mixed phase TiO 2 films exhibit higher conductivity, faster charge extraction, lower trap density and suppressed charge recombination at the interface of TiO 2 /perovskite films in the modified devices as well, achieving a champion power conversion efficiency of 15.21% for carbon based perovskite solar cells. More importantly, benefiting from the stable and better ultraviolet light filtration properties of rutile phase TiO 2 , our devices exhibit excellent stability maintaining 92% of their initial efficiency after 200 days storage in ambient air, highlighting their merits as a potential competitor for future industrial photovoltaics.