A single-molecule multicolor electrochromic device generated through medium engineering

Abstract

Multicolor organic electrochromic materials are important for the generation of full-color devices. However, achieving multiple colors using a single-molecule material has proved challenging. In this study, a multicolor electrochromic prototype device is generated by integrating medium engineering/in situ ‘electro base’/laminated electrode technologies with the simple flying fish-shaped methyl ketone TM1. This multicolor electrochromic (green, blue and magenta) device is durable and has a high coloration efficiency (350 cm2 C−1), a fast switching time (50 ms) and superior reversibility. This study is a successful attempt to integrate solvatochromism and basochromism in an electronic display. This integration not only introduces a new avenue for color tuning, in addition to the structural design of the colorant, but will also inspire further developments in the tuning of many other properties by this medium engineering approach, such as conductance and the redox property, and thereby accelerate versatile applications in data recording, ultrathin flexible displays, and optical communication and sensing. Using medium engineering, researchers in China have made a multicolour electrochromic device that employs a single organic compound. Organic electrochromic materials appear promising for meeting the high demand for low-power, ultrathin, flexible electronic displays but have so far been incapable of producing the three primary colours needed. Now, Yu-Mo Zhang and co-workers at Jilian University have produced a multicolour electrochromic device based on a single small-molecule organic compound, methyl ketone. They tuned the colour by varying the ratio of the two plasticizers used, allowing them to produce three primary colours. Their device has a fast switching time (50 ms), a large colouration efficiency (350 cm2 C–1) and a good reversibility. This medium-engineering approach has the potential to tune other properties and spawn applications in optical communication and sensing, data recording and ultrathin flexible displays.