Enhancing Viologen's Electrochromism by Incorporating Thiophene: A Step Toward All‐Organic Flexible Device

An all‐organic electrochromic device seems to be a possibility with ethyl viologen (EV) and poly‐3‐hexylthiophene (P3HT), both being organic materials, showing complementary electrochromic pair for color switching. The EV‐P3HT layer, sandwiched between ITO‐coated glass substrates shows switching between maroon and blue with an applied bias of 1.4 V. Mechanism of the color switching has been examined using UV‐Vis and Raman spectroscopies. The fabricated device shows optical modulation of 80%, switching time of 1 s while maintaining cycle life for a period of more than 600 s. The paradigm reported here inches toward realizing a flexible all‐organic electrochromic device.