A facile synthetic route to tungsten diselenide using a new precursor containing a long alkyl chain cation for multifunctional electronic and optoelectronic applications

Single source precursors for coating and subsequent thermal decomposition processes enable a large-scale, low-cost synthesis of two-dimensional transition metal dichalcogenides (TMDs). However, practical applications based on two-dimensional TMDs have been limited by the lack of applicable single source precursors for the synthesis of p-type TMDs including layered tungsten diselenide (WSe(2)). We firstly demonstrate the simple and facile synthesis of WSe(2) layers using a newly developed precursor that allows improved dispersibility and lower decomposition temperature. We study the thermal decomposition mechanism of three types of (Cat(+))(2)[WSe(4)] precursors to assess the most suitable precursor for the synthesis of WSe(2) layers. The resulting chemical and structural exploration of solution-processed WSe(2) layers suggests that the (CTA)(2)[WSe(4)] may be a promising precursor because it resulted in the formation of high-crystalline WSe(2). In addition, this study verifies the capability of WSe(2) layers for multifunctional applications in optoelectronic and electronic devices. The photocurrent of WSe(2)-based photodetectors shows an abrupt switching behavior under periodic illumination of visible or IR light. The extracted photoresponsivity values for WSe(2)-based photodetectors recorded at 0.5 V correspond to 26.3 mA W(−1) for visible light and 5.4 mA W(−1) for IR light. The WSe(2)-based field effect transistors exhibit unipolar p-channel transistor behavior with a carrier mobility of 0.45 cm(2) V(−1) s(−1) and an on-off ratio of ∼10.