Complementary Dual-Ligands Resurfacing CsPbI₃ Perovskite Quantum Dots for High-Performance Solar Cells

CsPbI₃ perovskite quantum dots (PQDs) emerge as promising optoelectronic materials for photovoltaics due to their high photoluminescence quantum yields and solution processability. However, the dynamic binding of long-chain ligands on the PQD surface generally induces numerous surface defects, which severely degrade the optoelectronic properties and stability of PQDs, to a large extent limiting the photovoltaic performance and operational stability of PQD solar cells (PQDSCs). Herein, a complementary dual-ligand reconstruction strategy is proposed to resurface the PQDs, in which the trimethyloxonium tetrafluoroborate and phenylethyl ammonium iodide can form a complementary dual-ligand system on the PQD surface through hydrogen bonds. The results reveal that the complementary dual-ligand system can not only stabilize the surface lattice of PQDs maintaining their good dispersion in the colloidal solution but also largely improve the inter-dot electronic coupling in the PQD solids. As a consequence, the PQDs demonstrate substantially improved optoelectronic properties and environmental stability, as well as a more uniform stacking orientation in the PQD solids, leading to a record high efficiency of up to 17.61% being realized in inorganic PQDSCs. This work provides a new avenue for the surface ligand engineering of PQDs for high-performance optoelectronic devices.