Hydrobromic acid-assisted size control of formamidinium lead bromide perovskite quantum dots at room temperature

Abstract

Formamidinium lead bromide perovskite (FAPbBr3) nanostructures have aroused increasing attention considering their excellent optoelectronic performance and higher stability than their MA- and Cs-based counterparts. Herein, we synthesized size-tunable FAPbBr3 quantum dots (QDs) at room temperature. The size of the perovskite QDs could be ajusted from 5.4 to 2.3 nm by just varying the amount of Hydrobromic Acid (HBr) added into the precursor. As a result, the photoluminescence (PL) emissions exhibited large blueshift from 531 to 446 nm due to quantum confinement effect. Quantum mechanical calculations of the optical gap fitted well with the experimental results. We found that the addition of HBr not only increased the concentration of the Br− but also protonated the oleylamine ligands. The two events synergically governed the size-decreasing effect of the QDs with increasing amount of HBr. The size-tunable FAPbBr3 QDs showed great application prospect in the field of photoelectric devices.