Study On Narrow Linewidth Luminescent Properties Of Organic Thin Films Based On Bloch Surface Waves

Organic semiconductor materials are widely used in many fields such as organic Light-Emitting diodes(OLED),organic semiconductor lasers,organic solar cells,due to their advantages such as low material and preparation cost,good flexibility,high fluorescence efficiency and wide spectrum coverage.After nearly 80 years of rapid development,organic semiconductor materials have been used in some fields,such as OLED display screens on mobile phones,flexible wearable devices,etc.Bloch Surface Wave(BSW)is a special surface electromagnetic wave,which exists in a local electromagnetic mode at the interface between one-dimensional photonic crystals with finite period and the external uniform medium.BSW has been widely studied and used in high sensitivity surface detection and fluorescence enhancement sources.In this paper,the luminescence properties of organic materials under the regulation of BSW mode are studied.The main research results are as follows:(1)By adding Pyrene into the PS matrix,the film was formed on the substrate with one-dimensional photonic crystal structure by spin coating.Narrow-band photoluminescence is observed in the direction parallel to the substrate surface.It is found that the peak of narrow-band spectrum can be adjusted by controlling the thickness of the organic layer,and the spectrum is redshifted when the thickness increases.Moreover,multiple narrow-band photoluminescence modes can be observed when the film thickness is large enough,which are closely related to the onedimensional photonic crystal structure and the outermost organic film thickness.(2)A simple and convenient BSW excitation method is found.PS:BSBCz thin film was prepared on the surface of one-dimensional photonic crystal.Under the pump of linear UV pulsed laser at 355 nm,the luminescence of BSBCz molecules regulated by BSW mode was observed.The main characteristics of BSBCZ molecule are narrow band,luminescence peak sensitive to the thickness of organic film,linear polarization,reduced fluorescence lifetime and enhanced fluorescence intensity effect.The minimum half-height and full width can reach 3 nm.Both amplified spontaneous emission and BSW mode emission can be observed with appropriate organic film thickness.