Off‐Grid Electrogenerated Chemiluminescence with Customized p‐i‐n Photodiodes

Abstract

Electrochemiluminescence (ECL) is the generation of light induced by an electrochemical reaction, driven by electricity. Here, an all‐optical ECL (AO–ECL) system is developped, which triggers ECL by the illumination of electrically autonomous “integrated” photoelectrochemical devices immersed in the electrolyte. Because these systems are made using small and cheap devices, they can be easily prepared and readily used by any laboratories. They are based on commercially available p‐i‐n Si photodiodes (≈1 € unit−1), coupled with well‐established ECL‐active and catalytic materials, directly coated onto the component leads by simple and fast wet processes. Here, a Pt coating (known for its high activity for reduction reactions) and carbon paint (known for its optimal ECL emission properties) are deposited at cathode and anode leads, respectively. In addition to its optimized light absorption properties, using the commercial p‐i‐n Si photodiode eliminates the need for a complicated manufacturing process. It is shown that the device can emit AO–ECL by illumination with polychromatic (simulated sunlight) or monochromatic (near IR) light sources to produce visible photons (425 nm) that can be easily observed by the naked eye or recorded with a smartphone camera. These low‐cost off‐grid AO‐ECL devices open broad opportunities for remote photodetection and portable bioanalytical tools.

All-Optical Electrochemiluminescence at Metal-Insulator-Semiconductor Diodes

“…Figure c and the corresponding photographs (Figure S7) show that the AO-ECL is influenced by the power density of the incident near-IR illumination. As seen in this 3D picture and plotted in Figure S8, AO-ECL intensity increases with P LED until a saturation is reached, as previously reported for AO-ECL at nanostructured Au- pnn ++ Si-Pt junctions and chemically modified commercial pin Si photodiodes Figure d reveals that AO-ECL is also strongly affected by the concentration of added H 2 O 2 and increases linearly in the 0–5.6 mM range.…”

“…Research on ECL generation at illuminated semiconductor surfaces (referred to as photoinduced ECL, PECL) − recently led to the concept of all-optical ECL (AO-ECL). , In AO-ECL, the photovoltage generated by a photoactive semiconductor junction allows inducing simultaneously the anodic ECL reactions and a cathodic counter-reaction at the junction’s reactive poles. It means that ECL is not produced in the dark, whereas, under illumination, photogenerated minority carriers drive redox reactions leading to visible emission, and photogenerated majority carriers are consumed by the counter-reaction .…”

“…Therefore, it represents a considerable step forward in the generalization of ECL. So far, AO-ECL has been demonstrated using the luminol-H 2 O 2 ECL system as the electrolyte, and photoactive devices based on Si buried junctions, i.e., nanostructured Au- pnn ++ Si-Pt junctions or chemically modified commercial pin Si photodiodes . In addition to being activated by polychromatic sunlight, AO-ECL can be triggered by monochromatic near-IR or red photons (λ exc input), generating blue photons (λ AO‑ECL output).…”

“…We expect that a similar concept can be employed in other ECL media, including ECL systems operating at physiological pH. Compared to other reported methods that involve buried pn or pin junctions , despite a low photovoltage, which can limits emission intensity, Pt/InGa/ n -Si/SiO x /Pt can be prepared by very simple means. This makes these results important for further developments of AO-ECL in sensing and microscopy.…”

Light Conversion by Electrochemiluminescence at Semiconductor Surfaces

“…All-optical ECL (AO-ECL) refers to wireless PECL systems that operate without an external power source. AO-ECL was inspired by research on monolithic water-splitting photoelectrochemical devices and can be considered as pushing and overcoming the limits of PECL to create a new electrically autonomous strategy. ,− In the reported AO-ECL systems, ,, which are based on Si, photogenerated holes and electrons trigger simultaneously the oxidative emission of visible ECL photons and the reduction of an oxidant present in solution, respectively. This can occur only if V OC (see Section ), generated by the photovoltaic junction, is higher than the overpotential required for triggering both the ECL oxidation and the cathodic counter-reduction.…”