Room Temperature Synthesis of Lead-Free Sn/Ge-Based Perovskite Quantum Dots

Metal halide perovskites have received remarkable attention as photovoltaic (PV) devices. These have already achieved power conversion efficiency higher than 23% rivaling that of silicon-based PV. However, these outstanding efficiencies can only be acquired with lead-based perovskites and the devices are chemically unstable in air and moisture. Therefore, the key to the widespread deployment of perovskite-based solar cell will come down to address their "toxicity" and instability problems. We have taken the challenge to replace lead with other nontoxic or less toxic elements, e.g., Sn, and Ge. We have synthesized Cs(Sn,Ge)X 3 (X=I, Br, and Cl) quantum dots (QDs) using room temperature process. The XRD data showed that the synthesized QDs were yellow hexagonal phase, which was further confirmed by the hexagonal shape of the TEM images of the crystals.