Enhancing selectively red spectral region by photonic crystals toward white light emission

The combination of red, green, blue (RGB) dyes and photonic crystals (PCs) is explored for white light application. The results show RGB emission is difficult to program by fluorescence resonance energy transfer, which is impossible to achieve the white light emission. When the PCs is used as an optical substrate, the green and blue spectral components obtain 2.7-3.5 times enhancement compared with the control sample due to large surface area of PCs. More importantly, the enhancement ratio of red spectral component is higher than that of the other color in the case of the stopband of PCs overlapping emission wavelength of Nile red, resulted from the enhanced light extraction of PCs, which makes up for the lack of red light, so that CIE coordinates are approaching to the white light region. The strategy will be of great guideline toward white light emission and play an important role on developing novel lighting devices.