Suppressed surface lattice vacancies and distortion through lattice anchoring for efficient FAPbI3 perovskite quantum dot solar cells

Abstract

Formamidinium lead triiodide perovskite quantum dots (FAPbI₃ PQDs) exhibit outstanding optoelectronic characteristics for new-generation solar cells. However, PQDs seriously suffer from surface lattice vacancies and lattice distortion, resulting in serious energy losses and low operational stability of PQD solar cells (PQDSCs). Herein, a feasible surface lattice anchoring (SLA) strategy is reported to stabilize the surface lattice of PQDs using the multifunctional molecule tetrafluoroborate methylammonium (FABF₄) for efficient solar cells. The results revealed that the FABF₄ molecule could effectively occupy the surface lattice vacancies and partly substitute the oleylamine and oleic acid ligands at the PQD surface, which benefits the charge carrier transport in PQD solids with lowered energy losses induced by the trap-assisted nonradiative recombination. Meanwhile, the BF₄⁻ anion could also stabilize the surface lattice of PQDs to substantially ameliorate the surface lattice distortion of PQDs, leading to an improved crystal stability of PQDs. Consequently, the PQDSCs constructed using the SLA-PQDs show a high efficiency of up to 17.06%, which is the highest efficiency of FAPbI₃ PQDSCs. This work provides important insights into the surface lattice modulation of PQDs for high-performance PQD optoelectronic devices.