Ligand Engineering of CsPbI₃ Quantum Dots for Efficient Solar Cells

Perovskite quantum dots (PQDs) have gained significantattentiondue to their exceptional optical and electronic properties, renderingthem promising materials for various optoelectronic applications,such as single-junction solar cells because of the multiple excitongeneration effects. To improve the electrical properties of CsPbI3 PQDs, ligand engineering was explored by introducing short-chainligands to exchange the original long-chain ligands on the PQD surfaceduring the purification process. However, the short-chain ligandssuffer from low solubility in the anti-solvent, resulting in insufficientligand exchange. To address this issue, we developed an in-situ ligandexchange (ILE) strategy to promote the replacement of long-chain ligandswith short-chain ones, leading to improved surface chemistry. In thiswork, 4-methoxyphenethylammonium iodide (CH3O-PEAI) wasdemonstrated as the short-chain ligand in the ILE strategy, therebymodifying halide vacancy trap states, and promoting carrier transportationand extraction. As a result, the ILE-CsPbI3-based solarcells achieved a higher power conversion efficiency of 14.4% witha high open circuit voltage (V (OC)) of 1.23V and exceptional long-term durability due to higher hydrophobicity.