Perovskite quantum dots (PQDs) have shown great promise in optoelectronic device applications. Typically, a traditional hot-injection method with heating and high vacuum pressure is used to synthesize these colloidal nanoparticles. In this article, we report a low-cost synthetic method for FAPbI3PQDs in air at atmospheric pressure with the assistance of ZnI2. Compared with the FAPbI3PQDs synthesized under vacuum/N2condition, the air-synthesized Zn:FAPbI3PQDs exhibit the same crystalline structure with a similar preferential crystallographic orientation but demonstrate higher colloidal stability and higher production yield. Furthermore, we examine the influence of ZnI2during the synthesis process on morphologies and optoelectronic properties. The results show that the mean size of the obtained FAPbI3PQDs is decreased by increasing the amount of added ZnI2. More importantly, introducing an optimal amount of ZnI2into the Pb source precursor enables increasing the carrier lifetime of FAPbI3PQDs, showing the potential beneficial effect on device performance.
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.
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