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

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 MoS 2 quantum dots (QDs) combined with UV–ozone (UVO) treatment. The optophysical properties and morphology of MoS 2 QDs and their photovoltaic performance are investigated. The results showed that MoS 2 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-MoS 2 QDs). The solar cells based on O-MoS 2 QDs yield a power conversion efficiency (PCE) of 8.66%, which is 71% and 12% higher than those of the OSCs with pristine MoS 2 QD and O-MoS 2 nanosheets, respectively, and the highest PCEs for OSCs containing MoS 2 materials. Furthermore, the stability of solar cells based on MoS 2 QDs is greatly improved in comparison with state-of-the-art PEDOT:PSS. These results demonstrate the great potential of O-MoS 2 QDs as an efficient HEL for high-performance OSCs.