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

Abstract 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‐Me₂) on MoS₂ 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⁻/Br₃⁻ redox pair, and a working electrode made with a dye‐sensitized TiO₂ photoanode integrated with PProDOT‐Me₂. 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 MoS₂ 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.