Published in Advanced Energy Materials: Multi-site coordination of perovskite surfaces by additives for enhanced crystallization and reduced defects

With multiple S=O groups, a signle molecule called OBSC can strongly bind to the Pb atoms at two perovskite grain surfaces, holding different grains together, enhancing crystallization, and reducing defects. These effects contribute to high-efficiency (certified 26.03%) and high-stability (T₉₆=1100h under one-sun continuous illumination) perovskite solar cells.

Abstract: Perovskite solar cells (PSCs) hold great promise as the next-generation low-cost photovoltaic technology due to their solution processability; however, this very advantage introduces intrinsic defects and microstructural imperfections, often limiting their performance and stability. Here, 4,4′-oxydibenzenesulfonyl chloride (OBSC), featuring a flexible backbone with two sulfonyl chloride (SO₂Cl) groups, is introduced as a bifunctional molecular additive to simultaneously passivate defects and regulate crystallization in perovskite films. The unique spatial configuration enables multi-site coordination, strongly binding to uncoordinated lead (Pb²⁺) via Pb−O interactions and interacting with formamidinium (FA⁺) through hydrogen bonding, effectively suppressing nonradiative recombination. Concurrently, OBSC stabilizes perovskite-solvent intermediate phases, retarding crystallization kinetics to promote the formation of high-quality films with enlarged grains and reduced trap densities. Consequently, the optimized PSCs demonstrated a champion power conversion efficiency (PCE) of 26.39% (certified 26.03%). Furthermore, the device retained 96% of the initial PCE after 1100 hours of continuous one-sun illumination. This work demonstrates the effectiveness of bifunctional additives in simultaneously addressing defects and crystallization issues, presenting a powerful strategy for achieving high-performance, stable perovskite photovoltaics.

This work is published in Advanced Energy Materials.

Acknowledgement

This work is a result of close collaboration of experimentalists (Prof Jun Peng’s group) and theorists (the nexSAS group). We acknowledge the financial support from ACAP and the computational resource from the Pawsey supercomputing centre of Australia.