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

Emerging 0D Transition‐Metal Dichalcogenides for Sensors, Biomedicine, and Clean Energy

“…So far, those researched solvents can be classified as water phase (e.g., sulfuric acid, surfactants aqueous solution), and organic solvents phase (e.g., N, N‐dimethylformamide (DMF), N‐methyl‐2‐pyrrolidone (NMP), isopropyl alcohol (IPA), and ethylene glycol) . For example, a sulfuric acid‐assisted ultrasonic route was provided for controllable‐size MoS 2 QDs with excellent PL properties through exfoliating and cutting bulk MoS 2 powder . Combining the sonication and solvothermal treatments, MoS 2 and WS 2 QDs with monolayer thickness were synthesized from their bulk crystals .…”

“…The photovoltaic performance of MoS 2 QDs were investigated and the results showed that the homogeneous films of MoS 2 QDs with desired photovoltaic performance could be applied not only as donors with shallow highest occupied molecular orbital (HOMO) but also for those with deep HOMO energy levels after UV‐ozone treatment. Meanwhile, the stability of solar cells based on MoS 2 QDs is remarkably improved, showing their significant potential as an efficient HEL for high‐performance organic solar cells (Figure b) …”

“…d) Specific capacitance of bare GC electrode modified with PANI/Pt and WS 2 NPs‐PANI/Pt microrobots at different current densities. a,b) Reproduced with permission . Copyright 2016, American Chemical Society.…”

“…Meanwhile, the strong quantum confinement effect further promotes the characteristic photoluminescence (PL) of 0D TMDs, making them interestingly useful in various fields. In addition, combining the desired biocompatibility, small size, and semiconductive properties, 0D TMDs have provided unprecedented opportunities for a series of sensing, biomedical, and energy applications ( Figure ) . So far, research on 0D TMDs nanostructures are still at their infant stage, where their potentials are still largely unexploited.…”

“…Copyright 2016, Wiley–VCH. (E5) Reproduced with permission . Copyright 2016, American Chemical Society.…”