One-pot synthesis of PbS quantum dots decorated with graphene for assisting charge carriers transport in bulk heterojunction solar cells

Abstract

The photocurrent of organic bulk heterojunction (BHJ) solar cells is improved by the introduction of PbS QDs decorated with graphene (G) in their photoactive layer. The insertion of PbS QDs:G is observed to improve the exciton dissociation and charge transfer paths. PbS QDs and PbS QDs:G are synthesized by the hot-injection method. The mechanism of PbS QDs formation and the role of their growth on G sheets are explained. Incorporation of PbS QDs and PbS QDs:G into the active layer of BHJ solar cells composed of poly (3-hexylthiophene-2,5-diyl) (El-Menyawy et al., 2019; El-Menyawy et al., 2019) [6,6]:-phenyl-C61-butyric acid methyl ester (P3HT:PC61BM) is found to improve their performance. The solar cells composed of pristine P3HT:PC61BM active layer are found to deliver a photoelectrical conversion efficiency (PCE) of 2.02 %. By inserting PbS QDs in the active layer, the PCE value is increased up to 2.44 %. Further increase in PCE to 3.27 % is explored by the inclusion of PbS QDs:G in the organic active layer. The ternary composites (P3HT:PbS QDs:G:PC61BM) have supreme characteristics, and are recommended for optoelectronic applications.