Bio-Hybrid White LEDs with Enhanced Photoluminescence via Förster Resonance Energy Transfer

Denice Feria^1*, Yu-Chien Tseng¹, Kai-Tse Kao¹, Tai-Yuan Lin¹

¹Department of Optoelectronics and Materials Technology, National Taiwan Ocean University, Keelung, Taiwan

* Presenter:Denice Feria, email:dnferia@email.ntou.edu.tw

Bio-hybrid white light-emitting diodes (BioHWLEDs) have emerged as a significant method for sustainable and environmentally friendly white lighting solutions. This study systematically investigated the photophysical properties of bio-phosphor-based WLEDs by utilizing layer-by-layer (LbL) structures composed of chlorophyll and albumen biomaterials. Steady-state photoluminescence (PL) measurements indicated a threefold increase in chlorophyll upon the addition of albumen to the pure chlorophyll structure. It also revealed a broader emission spectrum in green (523 nm) and red (684, 731 nm) regions as compared to the original PL spectra of the chlorophyll. Aside from the improved optical properties, a distinct spectral overlap was observed between the photoluminescence and absorption spectra of albumen and chlorophyll, indicating the presence of Förster-type resonance energy transfer (FRET). Time-resolved PL (TRPL) measurements revealed faster PL decay curves from the albumen within the LbL structure, indicating a significant energy transfer to chlorophyll and validating the presence of the FRET mechanism. The energy transfer mechanism in these two biomaterials was further elucidated by fabricating bio-phosphor-based WLEDs. Integrating a self-made blue LED (420 nm) with the bioinspired phosphor allows for the adjustment of color temperature through the modulation of the applied driving voltage, ranging from (0.27, 0.27) to (0.35, 0.31). The optimal chromaticity coordinates were found at (0.32, 0.30). Subsequently, after incorporating silk fibroin into the bio-phosphor LbL structure, the coordinates were further fine-tuned at (0.33, 0.30), providing a close approximation to the ideal values for white LEDs. The bio-phosphor-based WLEDs fabricated in this study demonstrate a significant development in green semiconductor technology and pave the way for eco-friendly white LED lighting sources.

Keywords: Bio-hybrid white light-emitting diodes (BioHWLEDs), chlorophyll, albumen , FRET, chromaticity coordinates