White light emission from a single plant source extract with tunable photoluminescence

Blue, yellow and red emissions from the extract of a single plant source (pomegranate), under NUV light excitation have been reported. The blue emission (450 nm) was attributed to baicalin and protein, whereas the yellow (550 nm) and red (665 nm) emissions were due to two kinds of anthocyanin components (A1 and A2, respectively). Both the green-to-white and yellow-to-white photoluminescences were tuned by variation of excitation wavelengths (350-400 nm). This change in photoluminescence was due to the occurrence of Forster resonance energy transfer from baicalin to A1. White light emission with good CIE color coordinates (0.34, 0.33) was obtained from the pomegranate pulp extract solution (12% w/v) at excitation of 350 nm. The results demonstrated that white light emission could be achieved from a single plant source, which would provide a new method for the design and fabrication of WLE with simple, green, and low-cost materials.