Hydrogen-Bonded Dopant-Free Hole Transport Material Enables Efficient and Stable Inverted Perovskite Solar Cells

Abstract

Although many dopant-free hole transport materials (HTMs) for perovskite solar cells (PSCs) have been investigated in the literature, novel and useful molecular designs for high-performance HTMs are still needed. In this work, a hydrogen-bonding association system (NH⋯CO) between amide and carbonyl is introduced into the pure HTM layer. Our study demonstrates that the hydrogen-bonding association can not only significantly increase the HTM’s hole transport mobility and functionalize the surface passivation to the perovskite layer, but also form Pb–N coordination bonds at the interface to promote the hole extraction while hindering the interfacial charge recombination. As a result, the PSCs based on dopant-free hydrogen-bonded HTMs can achieve a champion power conversion efficiency (PCE) of 21.62%, which is around 32% higher than the pristine PSC without the hydrogen-bonding association. Furthermore, the dopant-free hydrogen-bonded HTMs based device shows remarkable long-term light stability, retaining 87% of its original value after 500 h continuous illumination, measured at the maximum power point. This work not only provides a potential HTM with hydrogen-bonding association in PSCs, but also demonstrates that introducing hydrogen bonding into the materials is a useful and simple strategy for developing high-performance dopant-free HTMs.