Y. Zhao, J. Yu, G. Xu, N. Sojic, G. Loget
We introduce the photo-induced electrochemiluminescence (P-ECL) of the model ECL system involving the simultaneous oxidation of [Ru(bpy)3]2+ and tri-n-propylamine (TPrA). This system classically requires highly anodic potentials, >+1 V vs SCE for ECL generation. In the reported approach, the ECL emission is triggered by holes (h+) photogenerated in an n-type semiconductor (SC) electrode, which is normally highly challenging due to competing photocorrosion occurring on SC electrodes in aqueous electrolytes. We employ here Si-based tunnel electrodes protected by a few nm-thick SiOx and Ni stabilizing thin films and demonstrate that this construct allows generating P-ECL in water. This system is based on an upconversion process where light absorption at 810 nm induces ECL emission (635 nm) at a record low electrochemical potential of 0.5 V vs SCE. Neither this excitation wavelength nor this low applied potential is able to stimulate ECL light if applied separately. But their synergetic actions lead to a stable and intense ECL emission in water. This P‑ECL strategy can be extended to other luminophores and is promising for ultrasensitive detection, light-addressable and imaging devices.