Ionic liquid-regulated interfacial charge transport and asymmetric device architecture for high-performance...

Electrochemiluminescence (ECL) devices are promising alternatives to organic light-emitting diodes (OLEDs) and light-emitting capacitors (LECs) due to their simple structure and lower operating voltage, yet realizing sufficient luminance for practical applications remains challenging. Here, we report a synergistic material-device strategy for ultrabright electrochemiluminescent (UBECL) devices. Decoupling anion and cation effects reveals ion-dependent control of interfacial charge-transfer dynamics and electrochemical stability in annihilation-ECL. An effective electrolyte with favorable photophysical and electrochemical properties, coupled with an asymmetric device architecture, enhances electrochemical reactivity and maximizes ECL brightness. UBECL device turns on at a low alternating voltage (±1.65 V) and operates under high-frequency driving. It achieves a maximum luminance of 1552 cd m^-2 and 1.6 cd A^-1 current efficiency, a 3.2- and 2-fold improvement over 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (EMIMTFSI)-based counterparts. Moreover, this flexible UBECL platform enables diverse optoelectronic applications, including multicolor devices with potential for dynamic sensing, real-time digital panels, and robust underwater solid-state devices. This strategy unlocks ultrabright, efficient, high-frequency operation for intuitive visual output.