Electrochemical processes can be exploited to operate light-emitting devices with unusual functionality. For example, light-emitting electrochemical cells (LECs) contain a small amount of electrolyte within the organic/polymer light-emitting active layer. The electrolyte in the active layer allows the multiple charge injection layers that are deemed critical for organic light-emitting diodes to be avoided. Very recently, an alternative light-emitting device platform based on electrochemical processes was also suggested. These devices rely on electrochemiluminescence (ECL), a light-emission process based on the charge transfer reaction between reduced and oxidized forms of luminophores. Although the ECL process has been extensively investigated in the field of analytical chemistry, its utilization in electronic devices is a new approach that offers unique opportunities. Despite the interesting opportunities, a good introduction to the subject is not available, particularly with a focus on electronic device applications. Moreover, the operation of ECL devices is often confused with that of LECs, even though they follow distinct working principles. This confusion occurs mainly because the active layers for both ECL devices and LECs contain light-emitting material and electrolyte material (although their compositions are completely different). Therefore, clarifying the difference between the two sister devices would be both necessary and useful. In particular, a comparison of the two sister devices would highlight the unique opportunities for ECL devices and inspire researchers to devise a novel light-emitting device platform, which is the primary goal of this perspective.

Following early research efforts devoted to achieving excellent sensitivity of electronic skins, recent design schemes for these devices have focused on strategies for transduction of spatially resolved sensing data into straightforward user‐adaptive visual signals. Here, a material platform capable of transducing mechanical stimuli into visual readout is presented. The material layer comprises a mixture of an ionic transition metal complex luminophore and an ionic liquid (capable of producing electrochemiluminescence (ECL)) within a thermoplastic polyurethane matrix. The proposed material platform shows visco‐poroelastic response to mechanical stress, which induces a change in the distribution of the ionic luminophore in the film, which is referred to as the piezo‐ionic effect. This piezo‐ionic effect is exploited to develop a simple device containing the composite layer sandwiched between two electrodes, which is termed “ECL skin”. Emission from the ECL skin is examined, which increases with the applied normal/tensile stress. Additionally, locally applied stress to the ECL skin is spatially resolved and visualized without the use of spatially distributed arrays of pressure sensors. The simple fabrication and unique operation of the demonstrated ECL skin are expected to provide new insights into the design of materials for human–machine interactive electronic skins.

Electrochemiluminescence (ECL) involves light emission accompanied by a series of electrochemical processes on luminophores, which has been recently exploited in a new light-emitting device platform, referred to as the ECL device (ECLD). Here, we investigate the influence of the transport of the ECL luminophores and their reaction kinetics on the emission properties of alternating current–voltage-driven ECLDs. A model based on the diffusion and reaction rate equations is developed to predict the operational frequency (f)-dependent luminance properties of the ECLD. It is found that more frequent generation of the redox precursors with a shorter time interval enhances their probability of encountering each other, and therefore the luminance of the device increases with increasing f initially. The luminance at a higher f, however, is suppressed eventually due to the decreased rate of the electrode reactions. Using the model, the influence of diffusion and reaction rates on the performance of an ECLD is analyzed separately and systematically. The results provide insight on the operation of this emerging class of a light-emitting device platform.

As a new device platform comprising only electrochemiluminescence (ECL) luminophores and an electrolyte sandwiched between electrodes, ECL devices (ECLDs) promise to be cost efficient for large-area emissive applications. However, rapid degradation of luminescence, along with thermal decomposition of the electrochemical components, has proven a seemingly fundamental problem in ECLDs. To alleviate this issue, we investigated the influence of inserting a resting period during the operation of such devices by applying a square-shaped pulsed signal. The inserted resting period enhances the device stability, as it allows the effective reaction volume near the electrodes to be replenished with ECL luminophores, thus, preventing undesired side reactions. Moreover, the application of a current pulsed signal, rather than a voltage pulse, leads to further enhancement of the device stability, attributable to even distribution of the redox reaction over the rough surface of the electrode under current control. Under controlled pulsed-current operation (100 μA at 10 Hz), the emission characteristics of an ECLD employing a neutral iridium­(III) complex as the luminophore can be preserved for ∼1 h.

In article number 2100321, a material platform capable of transducing mechanical stimuli into visual readout is presented by Do Hwan Kim, Moon Sung Kang, and co‐workers. The electrochemiluminescent ionic materials embedded into a rubbery polymer matrix undergo visco‐poroelastic response to mechanical stress, resulting in the piezoionic effect. Locally applied stress can be spatially resolved and visualized via change in the luminescence.