Surface Matrix‐Mediated Cation Exchange of Perovskite Quantum Dots for Efficient Solar Cells
Guoliang Wang, Yuqi Sun, Xinyi Mei, Mingxu Zhang, Junming Qiu, Zhimei Sun, Zhimei Sun, Xiaoliang Zhang
Abstract
Abstract Cesium‐formamidinium lead triiodide perovskite quantum dot (Cs x FA 1‐x PbI 3 PQD) is very promising for photovoltaic applications due to its good phase stability and outstanding optoelectronic properties. However, achieving the Cs x FA 1‐x PbI 3 PQDs with tunable compositions and robust surface matrix remains a challenge. Here, the surface matrix‐mediated cation exchange of PQDs is proposed, in which a bi‐functional molecule, tetrafluoroborate methylammonium (FABF 4 ), is applied for the cation exchange and stabilizing surface matrix of PQDs. The results reveal that the FA + of FABF 4 molecules could exchange the Cs + of CsPbI 3 PQDs forming alloy Cs x FA 1‐x PbI 3 PQDs, allowing to tune the spectroscopies of PQDs. Meanwhile, the BF 4 − of FABF 4 molecules can effectively stabilize the surface lattice and substantially diminish the surface vacancies of PQDs, improving the phase stability and optoelectronic properties of PQDs. Consequently, Cs x FA 1‐x PbI 3 PQD solar cells deliver an efficiency of up to 17.49 %, which is the highest value of Cs x FA 1‐x PbI 3 PQD solar cells. This work provided important design principles for the composition and surface matrix regulation of PQDs for high‐performance solar cells or other optoelectronic devices.