2D-Layered Structure WS2 Nanosheets with Improved Electrochromism for Organic-Based Device

A solid-state electrochromic device is assembled via polythiophene (P3HT) and tungsten disulfide (WS 2 )-introduced ethyl viologen (EV) layers. The WS 2 nanosheets are prepared via a facile one-step hydrothermal technique and investigated via scanning electron microscopy, X-ray diffractometer and Raman spectra. The device exhibits the enhanced electrochromic properties, such as response time (0.9 s/1.3 s), cyclic stability (1000 cycles), coloration efficiency (410 cm 2 C −1 ), and the reversible color switching from pink to blue at the small applied potential (±1.6 V). This indicates that WS 2 with graphene-like 2D-layered nanostructure has the weak van der Waals force between the layers, which can store and transfer electrical charges between the films and electrolytes, thus improving the carrier mobility, which is crucial for improving the properties of electrochromic device. In addition, the introduction of WS 2 promoted the device to become one of the most efficient polythiophene-viologen based devices. Therefore, this work provides a basis for the development of new electrochromic devices as the alternatives to the graphene-based devices.