Surface Stress Engineering of CsPbI Perovskite Quantum Dots for Efficient Solar Cells.

Inorganic CsPbI perovskite quantum dots (PQDs) demonstrate high potential for new-generation photovoltaics, but the imbalanced surface stress of PQDs induced by ligand deficiency and incompatibility significantly deteriorates their optoelectronic properties and phase stability, restricting their photovoltaic performance. Herein, a surface lattice regularization strategy is proposed for the surface stress engineering of PQDs, in which a series of onium cations with appropriate dimensions and good affinity with the surface lattice of PQDs are introduced into the surface lattice of PQDs, resulting in substantially ameliorated optoelectronic properties and phase stability of PQDs. Meanwhile, with surface stress engineering, the PQD solid with enhanced stacking orientation is constructed, facilitating charge carrier transport. Consequently, the PQD solar cell with an efficiency of up to 17.01% is obtained, which is one of the highest values of inorganic PQD solar cells. Such a strategy provides feasible access to maximize the optoelectronic properties of PQDs for high-performance optoelectronics.