MoS₂ Quantum Dots with a Tunable Work Function for High-Performance Organic Solar Cells

Abstract

An efficient hole extraction layer (HEL) is critical to achieve high-performance organic solar cells (OSCs). In this study, we developed a pinhole-free and efficient HEL based on MoS₂ quantum dots (QDs) combined with UV-ozone (UVO) treatment. The optophysical properties and morphology of MoS₂ QDs and their photovoltaic performance are investigated. The results showed that MoS₂ QDs can form homogeneous films and can be applied as an interfacial layer not only for donors with shallow highest occupied molecular orbital (HOMO) but also for those with deep HOMO energy levels after UVO treatment (O-MoS₂ QDs). The solar cells based on O-MoS₂ QDs yield a power conversion efficiency (PCE) of 8.66%, which is 71% and 12% higher than those of the OSCs with pristine MoS₂ QD and O-MoS₂ nanosheets, respectively, and the highest PCEs for OSCs containing MoS₂ materials. Furthermore, the stability of solar cells based on MoS₂ QDs is greatly improved in comparison with state-of-the-art PEDOT:PSS. These results demonstrate the great potential of O-MoS₂ QDs as an efficient HEL for high-performance OSCs.