Dual-anchored configuration involving Pb(NO3)2 for effective and stable FAPbI3 quantum dot solar cells

The dynamic nature of formamidine lead iodide quantum dots (FAPbI3 QDs) limits their practical application by causing the appearance of ionic vacancy defects on the surface of QDs, which would then allow for significant trap-assisted non-radiative recombination of charge carriers. Herein, we explore a feasible surface modification strategy for passivating vacancy defects. Different lead salts are employed in the post-treatment procedure of quantum dot films. Based on both experimental and theoretical findings, Pb(NO3)2 passivation comprises Pb2+ and FA+. On the quantum dot surface, the O atoms from NO−3 form strong chemical bonds with FA+, and the O–C⋯O–N structure, defined by a dual-anchored configuration, contributes to the establishment of a stable crystal structure by exhibiting optimal bond lengths (3.486 Å and 3.775 Å, respectively) and a higher binding energy (10.51 eV). Finally, FAPbI3 quantum dot solar cells simultaneously achieve both exceptional environmental stability and a champion photoelectric conversion efficiency of 12.11%. This work provides valuable insights into surface chemical engineering of quantum dots, paving the way for high-performing photovoltaic devices.