Light‐Emitting Devices Based on Electrochemiluminescence Gels

Electrochemiluminescence (ECL) is a self‐emission of light from electrochemically excited luminophores via a series of redox reactions. Over the past decade, light‐emitting devices based on gel‐phase ECL active materials, i.e., gel electrolyte composites (referred to as ECL gels) containing an ECL luminophore, electrolyte, and network matrix, have attracted considerable attention as a complementary device platform to conventional electroluminescent devices for low‐cost printable displays and solid‐state light sources. Although the ECL phenomenon is extensively exploited in analytical diagnostics and sensing, the development of printable and fast‐response gel‐type luminescent materials may further expand the potential application of ECL in solid‐state flexible, bendable, and stretchable light‐emitting devices. This review summarizes the operation mechanisms of ECL‐based light‐emitting devices, ECL emitters and electrolytes, engineering strategies for obtaining printable high‐strength/high‐conductivity ECL gels, and emerging applications of gel‐type ECL devices. Recently developed gel‐type electrochemiluminescence devices (ECLDs) have attracted attention for low‐cost printable displays owing to their simple device structure, high moisture/oxygen tolerance, low operation voltage, and mechanical flexibility/stretchability. This review covers the recent progress regarding the operation mechanisms, materials, and design considerations for gel‐type ECLDs with the aim of achieving high‐conductivity/high‐strength ECL gels, and new opportunities for exploiting ECLDs.