Enhanced photovoltaic performance of SnO2 based flexible perovskite solar cells via introducing interfacial dipolar layer and defect passivation

Abstract

Low processing temperature of tin dioxide (SnO 2 ) is essential for flexible perovskite solar cells (f-PSCs). However, the low processing temperature of SnO 2 results in an inferior photovoltaic performance due to compromised carrier transport capacity in devices. The deteriorated carrier transport mainly results from the suppressed interfacial charge transfer. To overcome these issues, we used ionic liquid to modify the interface between perovskite films and SnO 2 in f-PSCs. Density Function Theory calculations were implemented to demonstrate the ionic liquid modification induced the formation of interfacial dipolar layer (IDL) and defect passivation in perovskites. The IDL and defect passivation improves the interfacial charge transfer and intra-perovskite charge transport, respectively. As a result, the f-PSCs based on ionic liquid modified SnO 2 yield the champion power conversion efficiency (PCE) of 19.0%. This work provides a method to effectively improve the performance of f-PSCs using low-temperature processed SnO 2 ESLs using affordable materials and a facile approach. • Ionic liquid is used to form an interfacial dipole layer (IDL). • Ionic liquid can also passivate defects in perovskite. • IDL and defects passivation contribute to the performance improvement of f-PSCs. • All fabrication processes of f-PSCs are conducted at the low temperature (≤100 °C). • Power conversion efficiency of f-PSCs is improved from 13.5% to 18.1%.