Stability studies of colloidal indium phosphide quantum dots: Humidity-induced photoluminescence enhancement

Abstract

InP quantum dots (QDs) and InP/ZnS core shell structures were synthesized using one pot hot injection technique. An increment in the PL intensity was seen after the growth of ZnS shell. A post synthesis HF treatment is given to the QDs in order to increase the PL intensity by removing surface defects. Humidity studies were done to observe the stability of InP QDs, treated InP and InP/ZnS QDs. An unusal increment in the PL intensity was observed for InP upon exposure to humidity. Within two weeks the PL intensity increased by 118 % without much change in the peak position. This can be attributed to the water molecules which get adsorbed on the surface of QDs and results in surface passivation. A similar trend was observed for treated InP QDs but in the second week, the PL increment was saturated and did not increase further. InP/ZnS showed a decrement in the PL intensity on exposure because it is robust to oxidation due to the formation of shell.