Supercritical Synthesis and Characterization of Graphene-PbS Quantum Dots Composite with Enhanced Photovoltaic Properties

Lead sulfide quantum dots (PbS QDs) were decorated onto a graphene surface in a semi-core shell Structure. using supercritical ethanol. The temperature of ethanol played significant role in controlling size and agglomeration Of QDs as well as the extent of reduction of graphene. Average size Of the QDS was estimated by transmission electron microscopy to be around 3.96 nm and by quantum models to be about 4.34 mu. PbS QDs prepared at 330 degrees C were of high purity,. and the yield was 99%. Instrumental- and chemical analyses demonstrated formation of a strong bond betv between PbS QDs and, graphene, through a Pb-O-C bridge. tIV and photoluminescence measurements along with -theoretical considerations revealed that integration of PbS QDs with grapherie'results in efficient separation of the electron hole, thus enhancing photo electric energy conversion. This Outcome was further evidenced by comparison of performance of PbS/G in a Solar cell, with the performance of pristine PbS QDs.