Tandem FRET: A Robust Mechanism for Efficient Fabrication of WLED Using an Organic–Inorganic Hybrid Mixture

This article highlights the development of an affordable white light-emitting material achieved through a sequential energy transfer process involving zinc oxide, bismuth (III) oxide, and Nile blue. ZnO and Bi2O3 were synthesized using a simple co-precipitation method, and Nile blue A was used as purchased. Conventional Forster Resonance Energy Transfer has been observed between the ZnO–Bi2O3 pair and the Bi2O3–Nile blue pairs. The decrease in steady-state fluorescence intensity has also been substantiated by a reduction in the fluorescence lifetime. When subjected to excitation at 370 nm, the mixtures of ZnO–Bi2O3–Nile blue exhibited emission spectra spanning the entire visible range. Here, Bi2O3 acts as an antenna in transferring the energy nonradiatively from ZnO to Nile blue, thereby facilitating cascaded FRET. The dye-nanohybrid mixture and PVA hydrogel were blended thoroughly and coated over a UV-LED to obtain a white LED. The electroluminescence spectra exhibited emission in the entire visible region. The obtained CIE coordinates of the fabricated WLED were (0.31, 0.33), close to pure white, with a color correlated temperature of 5639 K and a color rendering index of 95. The advent of this straightforward dye-nanohybrid mixture brings us closer to the possibility of designing a light-harvesting system suitable for implementation in display technology.