Novel eco-friendly dye-polymer composite films for white LEDs: Syntheses, structures and luminescence properties

Natural luminescent dyes exhibit great potential in white light-emitting diodes (LEDs) due to their non-toxicity, low cost, and environmental compatibility. However, traditional natural luminescent dyes show aggregation-caused quenching and thermally unstable luminescence. Therefore, developing novel natural luminescent dye-based composite materials to overcome these limitations is highly desirable for white LEDs. In this work, BBR-PVA composite films are synthesized with different BBR concentrations through a simple dip-coating method. The structures and luminescent properties of BBR-PVA composite films are investigated. Results demonstrate the formation of BBR J-aggregates in the composite, enhancing the luminescence of BBR-PVA composite films. The presence of intermolecular H-bonds between BBR and PVA molecules improves lumines-cent thermal stability. Moreover, the relative contributions of BBR J-aggregation and H-bonding interactions to the luminescence of the composites are tuned by varying the BBR concentration. The white LED fabricated using a blue chip and the as-synthesized BBR-PVA composite film shows good luminescence performance at 2.7 V and a driving current of 57 mA. The CIE chromaticity coordinates, the correlated color temperature, color rendering index, and luminous efficiency are (0.32, 0.25), 7238 K, 75 and 12 l m/W, respectively.