Photovoltaic performance improvement of organic solar cell with ZnO nanorod arrays as electron transport layer using carbon quantum dots-incorporated photoactive layer

Abstract

The carbon quantum dots (CQDs) with astonishing optical and electrical features have been utilized to improve the photovoltaic performance of organic solar cells (OSCs). In this work, CQDs dispersed in isopropanol were incorporated into photoactive layer of poly(3-hexylthiophene) (P3HT):(6,6)-phenyl-C61-butyric acid methyl ester (PC61BM) with different volume concentrations (0, 20, 40, 60 and 80 vt%). ZnO nanorod arrays, serving as the electron transport layer, was prepared on ZnO seed layer-coated fluorine-doped tin oxide (FTO) glass substrates. The CQDs-incorporated P3HT:PC61BM photoactive layers were then spin-coated on top of ZnO and silver (Ag), acting as the top electrode, was deposited via thermal evaporation method. It was found that 40 vt% CQDs-incorporated device demonstrated the highest power conversion efficiency and enhancement of 37% compared to that of the device without CQDs. It is proven that the introduction of CQDs improves the optical absorption, exciton dissociation and charge transport of the OSCs.