Ultraviolet-C emitting device based on Bi3+-activated orthophosphate films in electrolyte-assisted silicon semiconductor

Electrolyte-assisted semiconductors have garnered significant interest as an innovative category and promising candidates for the development of modern electronics. Herein, we propose an optoelectronic device based on an electrolyte-assisted semiconductor, so-called electrolyte-assisted electroluminescence (EEL) with ultraviolet-C (UVC) emission from Bi³⁺-activated orthophosphate films. The electrolyte in this approach acts as the carrier transfer layer generated from the electrochemical reaction during the sinusoidal source operation. By incorporating Bi³⁺ ions into lanthanum orthophosphate films (YPO₄ and LuPO₄), a UVC emission peaking at 251 nm is observed, attributed to electronic transitions of Bi³⁺ within the host lattices. Compared to traditional EL devices, our EEL device operates at a lower voltage and frequency (30 V, 50 Hz), reducing the load on electrical sources. Additionally, it demonstrates decent reliability, maintaining 50 % of its emission intensity after 20 min of continuous operation without any encapsulation. Moreover, compared to other UVC sources, our EEL device offers advantages such as a low-cost manufacturing process and being mercury-free. Thus, this approach could further expand the practical application of the electrolyte-based semiconductor that emits UVC for sterilization technology.