Synthesis of atomically thin alloyed molybdenum-tungsten disulfides thin films as hole transport layers in organic light-emitting diodes

The hole transport properties of MoS2/WS2 heterojunction and alloyed Mo1−XWXS2 thin films, prepared using mixed solution precursors, in OLEDs were investigated in terms of improvement in device performance and stability in air. The alloyed Mo1−XWXS2 thin films can act as improved hole transport layers compared to PEDOT:PSS layers. [Display omitted] •Mo1−XWXS2 thin films are synthesized via simple thermal disproportionation methods.•Alloyed TMD was used as hole transport layers (HTL) in organic light-emitting diodes.•The Mo0.4W0.6S2 HTL device shows an improved efficiency and enhanced air stability.•The Mo1−XWXS2 HTL may replace the conventional HTL. Two-dimensional transition metal dichalcogenides (TMDs) have been intensively researched due to their excellent physical, chemical, and mechanical properties, which make them essential for various electronic devices owing to several disadvantages of conventional hole-transport layers (HTLs) such as hygroscopic effect and highly acidic nature, which can induce low stability of the fabricated devices. Especially, they have been considered as hole-transport layers (HTLs) in organic light-emitting diodes (OLEDs) and organic photovoltaics due to its chemical stability. Despite of its adequate work-function value and chemical stability, the device stability could be enhanced but, device performance of pristine TMD-HTL-based has been reported lower than conventional devices. In this work, we report a facile route to synthesize alloyed transition metal disulfides (TMD) thin films and their application as hole transport layers in OLEDs. Polycrystalline, large-area, and uniform Mo1−XWXS2 thin films are synthesized via simple thermal disproportionation methods by chemical vapour deposition. The physical and chemical properties of the synthesized alloyed TMD layers are controlled by varying the precursor concentrations. The device performance of alloyed TMD-layer-based OLED is comparable to that of conventional poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) (PEDOT:PSS) and device stability in air is significantly improved. Thus, a novel approach to synthesize alloyed Mo1−XWXS2 thin films and their application in optoelectronic devices are presented herein.