Research On Room Temperature Controlled Synthesis And Photostability Of Bismuth Halide Perovskite Quantum Dots

In recent years,lead halide perovskite quantum dots?QDs? have attracted intensive interest due to their unique optoelectronic properties and been widely applied into photodiodes,solar cells,optical detectors,biomarkers and other fields.However,the toxic lead element will cause serious harm to human body and ecosystem,and the presence of lead element seriously hinders the commercial application of lead halogen-perovskite quantum dots.Therefore,the synthesis of environmentally friendly lead-free perovskite quantum dots is of great significance.Herein,from the large number of elements which could be the candidates to replace lead in perovskite QDs,bismuth was selected as the study object,due to the low toxicity and excellent stability of bismuth-based compounds.In this present work,?CH₃NH₃?₃Bi₂Br₉ and Cs₃Bi₂Br₉ perovskite QDs were successfully synthesized at room temperature and characterized.There are two synthesis methods were adopted in this work,one is ligand-assisted re-precipitation?LARP?,another one is non-polar solvent at room temperature synthesis method?NPRT?.It was found that compared to Cs₃Bi₂Br₉ QDs,the performance of?CH₃NH₃?₃Bi₂Br₉ QDs synthesized by LARP was unsatisfactory,while the all-inorganic Cs₃Bi₂Br₉ perovskite QDs synthesized with NPRT showed tremendous superiority to Cs₃Bi₂Br₉ synthesized by LARP.What's more,Cs₃Bi₂Br₉ perovskite QDs synthesized with NPRT showed blue dual-emission peaks at 414 nm and 433 nm with a full width at half-maximum?FWHM?of 50nm,photoluminescence quantum yield?PLQY? up to 29.6%,and good stability during the three-week storage in air.Furthermore,it was also found that potassium oleate?K-OA? solution could enhance the PL intensity of Cs₃Bi₂Br₉ perovskite QDs.