Synthesis and characterization of Rb ₃ Sb ₂ Br ₉ perovskite quantum dots

Although lead (Pb)-containing perovskite quantum dots have shown great potential in various fields of applications such as light-emitting diodes, solar cells and displays, due to the toxicity of Pb and its chemical instability, commercialization of Pb-perovskite-based products has not yet been realized. Hence, it is necessary to look for other metals, environmentally much safer than Pb, to replace Pb. Because tin (Sn) and germanium (Ge), which are in the same group as Pb, show some instability due to oxidation of +2 states to +4 states, bismuth (Bi) and antimony (Sb) are more viable choices to replace Pb as Bi and Sb form +3 ions with electronic configurations similar to that of Pb ²⁺ . We report the synthesis of environmentally safe, lead-free Rb3Sb2Br9 perovskite quantum dots (PQDs) by using a modified ligand-assisted reprecipitation (m-LARP) technique and their properties to demonstrate the possibility of using them in diverse fields of applications. Our lead-free PQDs are tens of nanometers wide and less than 2 nm in height, showing a fairly uniform size distribution. Optical characterization of these PQDs shows a considerable absorption in the UV region and some photoluminescence around 400 nm.