Polythiophene–PCBM-Based All-Organic Electrochromic Device: Fast and Flexible

A fast and flexible all-organic electrochromic device, fabricated using polythiophene and PCBM as active materials and plastic substrate, which shows very good power efficiency as well, has been reported here. The device shows quantifiable improvement in electrochromic performance using parameters like switching speed, coloration efficiency, color contrast, and cycle life. Spectroscopic investigations have been carried out using Raman and UV–vis to establish a bias induced redox switching based mechanism for the reported improvement in the performance. The device shows switching between magenta (OFF) and transparent states (ON) with a very small bias of ±1 V, an optical modulation of 50% and an absorbance switching contrast of 91%. An enhanced stability for a duration of longer than 2500 s and 250 cycles has been reported with an ultrafast response of few hundred milliseconds. A very high coloration efficiency of 321 cm2/C is achieved, making the proposed device one of the best reported P3HT-based electrochromic devices.