Rapid and room temperature synthesis of MAPb1-xSnxBr3-2xCl2x perovskite quantum dots with enhanced lifetime in warm WLEDs: A step towards environmental friendly perovskite light harvester

In this work, a facile approach to develop nontoxic CH3NH3PbBr3 perovskite quantum dots (PQDs) by substituting tin (Sn2+) ion instead of lead (Pb2+) ion and chloride (Cl-) ion instead of bromide (Br-) ion has been reported. Synchronized cation and anion substitution in CH3NH3Pb1-xSnxBr3-2xCl2x PQDs has resulted in commercial-friendly properties like fine-tuning of bandgap, shifting of color emission from green to cyan region (523 nm-490 nm), enhancing structural stability, excitonic lifetime, and color gamut. Presence of Sn2+ cations in +2 state, Cl- anions in -1 state, and ion exchange was confirmed from various spectroscopic and morphological analyses. Photoluminescence quantum yield (PLQY) for unsubstituted CH3NH3PbBr3 was observed as 97.50% and it is reduced to > 50% for 15% SnCl2 substituted CH3NH3PbBr3 PQDs because of the presence of defect-related nonradioactive recombination centres while cation and anion changeover. Warm white LED prototype with 123% color gamut encircling as per National Television System Committee Standard was achieved using as prepared CH3NH3Pb1-xSnxBr3-2xCl2x PQDs and commercial red phosphor on the blue LED chip. The inflated colour-gamut, promising PLQY, and slender FWHM of as-synthesized CH3NH3Pb1-xSnxBr3-2xCl2x PQDs illustrate great prospect to explore their utilization in display applications. Reduction in toxicity in perovskite material was confirmed by the biological study.