Investigation On Energy Transfer Of Luminophors Modulated By Photonic Band Gap Structure

The presence of the photonic band gap structure (referred as photonic crystals) not only leads to appearances of lots of new materials and devices but also creates a specific physical environment, i.e. a periodically dielectric field on the wave length scale.The optical property and energy transfer of photoelectric materials may be modulated by the periodically dielectric field on the wave length scale. In this paper, the photonic crystals with different structures have been designed and prepared, and the influences of the three dimensional photonic gap (pseudo-gap) on the optical behavior and energy transfer of the luminophors have been analyzed.The dye-doped opal photonic crystal was prepared by the vertical deposition method. The energy transfer from Fluorescein to Rhodamine B was investigated through both stable fluorescence spectroscopy and time-resolved spectroscopy. The results show that when the emission peak of the donor Fluorescein overlaps the photonic band gap of the opal photonic crystals, the spontaneous emission of the donor is inhibited. The inhibition of the spontaneous emission of the donor results in a fact that the excitation state donor could returns to the ground state more easily by the energy transfer. That is, the energy transfer of dyes in the photonic crystals can be enhanced.The Tb1-XEuXPO4 (X=0, 0.001, 0.0025) inverse opal photonic crystals were prepared by the accelerated evaporation induced self-assembly technique in combination with a sol-gel method. The photoluminescence of inverse opal was studied by fluorescence microscope. The energy transfer enhancement between rare earth ions was first observed experimentally in the inverse opal photonic crystals. Inverse opal photonic crystals of TbPO4 with coexistence of the (100) and (111) orientations were prepared. Optical and photoluminescence properties of the (100) and (111) orientations regions were investigated in TbPO4 inverse opals. It was found that the photonic bandgap of (100) orientation shifted to shorter wavelengths compared with that of (111) orientation in the inverse opals. The effect of the photonic bandgap on the spontaneous emission of the 5D4→7Fn transitions of Tb3+ was observed in the TbPO4 inverse opals with coexistence of the (100) and (111) orientations. Significant suppression of the emission was detected in the (111) orientation regions.The ions exchange method was used to prepare crystalline colloidal arrays, in which the non-radiative energy transfer between fluorescence dyes was investigated. It has been verified that the energy transfer between fluorescence dyes can be enhanced by the photonic band gap of the crystalline colloidal arrays. Meanwhile, the energy transfer enhancement difference was first investigated when the overlaps between the photonic band gap and the donor's emission peak was different. It has been revealed that the energy transfer and the radiative emission are related to the overlap between donor emission band and photonic band gap. The more overlapping between donor emission band and photonic band gap is, the more difficult the radiative emission is, contrarily, the stronger the energy transfer is.The polymerized crystalline colloidal arrays were prepared by situ polymerization method. The influence of photonic band gap on photoluminescence of dyes was investigated. Suppression of the emission was observed if the photonic bandgap overlapped with the dyes emission band in the polymerized crystalline colloidal arrays.