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

摘要

Single source precursors for coating and subsequent thermal decomposition processes enable a largescale, 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 (WSe2). We firstly demonstrate the simple and facile synthesis of WSe2 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)[WSe4] precursors to assess the most suitable precursor for the synthesis of WSe2 layers. The resulting chemical and structural exploration of solutionprocessed WSe2 layers suggests that the (CTA) (2)[WSe4] may be a promising precursor because it resulted in the formation of high-crystalline WSe2. In addition, this study verifies the capability of WSe2 layers for multifunctional applications in optoelectronic and electronic devices. The photocurrent of WSe2-based photodetectors shows an abrupt switching behavior under periodic illumination of visible or IR light. The extracted photoresponsivity values for WSe2-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 WSe2-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 similar to 10.