Synergistic Improvement of Structural Ordering and Interface Binding of Hole Transport Monolayer for Efficient Inverted Perovskite Solar Cells

A co-assembled molecule that can help form homogenized and structural ordered hole transport monolayer, while improving interfacial strength and maintaining the long-term integrity of the bottom interface, has been employed to achieve efficient and stable inverted perovskite solar cells based on self-assembled monolayer.

Abstract

The widespread application of self-assembled monolayer (SAM) hole transport materials has driven rapid advancements in the performance of inverted perovskite solar cells (PSCs). However, the difficulty of achieving a highly ordered SAM for hole transport and the weak binding strength between SAM and the perovskite layer not only leads to defective bottom interface but also reduces the compatibility with the large-area device fabrication. In this work, a co-assembled molecule functionalized with a diamide terminal group is demonstrated that is able to form supramolecular interaction with popular carbazole-based SAMs for regulating their structural ordering, and to improve the chemical bonding with perovskite Pb-I frameworks synergistically, which enables efficient and long-term stable inverted PSCs. As a result, the target co-assembled SAM contributes to a champion small-area device with a power conversion efficiency (PCE) of 25.3% (certified 25.0%), and demonstrates good compatibility with large-area fabrication by achieving highly reproducible performances in 1.02 cm² devices. The encapsulated devices exhibit good stability with 92.8% and 91.2% of initial PCE after 1500 hours of aging under 85 °C and maximum power point (MPP) tracking at 65 °C for 1500 hours, respectively.