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

Abstract

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.