Dual Passivation of CsPbI3 Perovskite Nanocrystals with Amino Acid Ligands for Efficient Quantum Dot Solar Cells

Inorganic CsPbI3 perovskite quantum dot (PQD) receives increasing attention for the application in the new generation solar cells, but the defects on the surface of PQDs significantly affect the photovoltaic performance and stability of solar cells. Herein, the amino acids are used as dual‐passivation ligands to passivate the surface defects of CsPbI3 PQDs using a facile single‐step ligand exchange strategy. The PQD surface properties are investigated in depth by combining experimental studies and theoretical calculation approaches. The PQD solid films with amino acids as dual‐passivation ligands on the PQD surface are thoroughly characterized using extensive techniques, which reveal that the glycine ligand can significantly improve defect passivation of PQDs and therefore diminish charge carrier recombination in the PQD solid. The power conversion efficiency (PCE) of the glycine‐based PQD solar cell (PQDSC) is improved by 16.9% compared with that of the traditional PQDSC fabricated with Pb(NO3)2 treating the PQD surface, owning to improved charge carrier extraction. Theoretical calculations are carried out to comprehensively understand the thermodynamic feasibility and favorable charge density distribution on the PQD surface with a dual‐passivation ligand. Improved defect passivation of perovskite quantum dots (PQDs) is reported using glycine as a dual‐passivation ligand, which can simultaneously fill the A‐site (cesium) and iodine vacancies on the PQD surface. The enhanced photovoltaic performance is obtained in the glycine‐based PQD solar cells (PQDSCs) compared with that of the traditional Pb(NO3)2‐based PQDSCs, resulting from increased charge carrier extraction.