Electroswitchable optical device enabling both luminescence and coloration control consisted of fluoran dye and 1,4-benzoquinone

• An electrochemically modulated optical device was developed.
• 1,4-Benzoquinone acts as a bifunctional electrochromic and change balance mediator.
• Color and luminescence switching can be controlled based on electrical stimuli.
• Yellow-1 is a fluoran derivative whose color and emission are switched.

An electroswitching device that enables modulation of both emission and coloration was obtained by combining luminesncent/electrochromic (EC) molecules of a fluoran molecule (Yellow-1) and 1,4-benzoquinone (BQ). Electroswitching of emission and coloration was achieved by the reversible electrochemically induced closing and opening of the lactone ring in Yellow-1. Neutral Yellow-1 was colorless and did not exhibit any fluorescence, while oxidized Yellow-1 (lactone ring-opened form) was yellow and displayed green fluorescence because of its extended, planar, and conjugated system. In order to achieve quick response time and high reversibility of the electroswitching optical device for modulating both emission and coloration, a BQ molecule was introduced as a bifunctional material. The inclusion of a redox-active moiety on the auxiliary electrode maintained the charge balance and acted as an EC molecule (transparent/yellow in neutral/reduced state, respectively). BQ acted as a bifunctional molecule, leading to quick and stable switching of both emission and coloration.

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