Designing conductive fullerenes ionene polymers as efficient cathode interlayer to improve inverted perovskite solar cells efficiency and stability

Abstract

Unsatisfactory interface contacts and energy level barrier between adjacent interlayers are important issues that hinder the improvement of the perovskite solar cells (PSCs). A novel and efficient conducting cathode interlayer for PSCs is synthesized in this work by combining ionene polymer with pendent fullerene. This novel n-doping fullerene ionene polymer (C60-MPE-ionene) is developed as a cathode interlayer to enhance interface contact, tune work function of metal cathode and reduce energy level barrier. Due to the introduction of fullerene to the side chain remarkably improves conductivity of ionene polymers, the high efficiency devices can be obtained by depressing charge accumulation at the cathode/electron transfer layer (ETL) interface. Hence, the device based on C60-MPE-ionene as cathode interlayer achieves a high efficiency of 19.28%, which is significantly higher than the finding of control devices (15.60%). Moreover, hydrophobic conductive fullerene ionene polymers dramastically enhance the resistance of perovskite films to moisture. Our study shows the promising potentials of fullerene ionene polymers as the cathode interlayer in PSCs and provides new insights into the development of new cathode modification materials in the future.