Partly Covered PProDOT-Me2 on MoS2 Nanosheets Counter Electrode for High-Performance Self-Powered Electrochromic Device

Developing a low-cost and transparent counter electrode (CE) for a self-powered electrochromic device (SP-ECD) can address the requirements of building-integrated photovoltaics (BIPVs). Herein, a new partly covered poly(3,4-(2,2-dimethylpropylenedioxy) thiophene) (PProDOT-Me 2 ) on MoS 2 nanosheets CE is developed for replacing an expensive Pt CE and achieving high-performance SP-ECD. The device consists of the proposed CE, an electrolyte containing Br − /Br 3 − redox pair, and a working electrode made with a dye-sensitized TiO 2 photoanode integrated with PProDOT-Me 2 . ECD changes its color between deep blue and colorless by varying the illuminated light on and off. Measurements reveal that the ECD achieves a transmittance modulation of 46% at 580 nm with cycling stability over 500 cycles (4% contrast attenuation) that are about five times stable than that based on Pt or MoS 2 CE. In addition, the switching speed between colored and bleached states is fast under a light on and off, with a coloration time of 2.1 s and a bleaching time of 1.5 s. These characteristics result from the unique design of CE and can be beneficial in accelerating the electrochromic process and enhancing the self-powered performance for good cycling stability. This study reveals a new approach to prepare good CE for efficient SP-ECD in BIPVs.