Surface engineering in CsPbX3 quantum dots: from materials to solar cells

Lead halide perovskite quantum dots (PQDs) are considered to be one of the most promising classes of photoactive materials for solar cells due to their prominent optoelectronic properties and simple preparation techniques. Even though the high resistivity of these PQDs toward defect formation results in compelling optical properties and their manifestation in device applications, they are not free from defects, and their photoluminescence quantum yield is often not unity. Defects and ligands at the surface of PQDs play a critical role in charge transport and non-radiative recombination, which lowers the solar cell efficiency and stability. Therefore, understanding the defects and developing effective passivation routes are critical for achieving advances in device performance. In this review, we focus on the surface engineering of CsPbX3 PQDs, including the formation of surface vacancy defects and the surface ligand modification of PQDs, and then summarize the corresponding surface defect passivation strategy for systematically improving the performance of PQD solar cells. At the end, a brief summary and perspective are presented looking forward to the future development of PQD solar cells.