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Organic light emitting materials : amplified spontaneous emission and hybrid inorganic-organic white light emitters

Authors Yue, Zhounan
Issue Date 2011
Summary Amplified spontaneous emission (ASE) from F8BT and MEH-PPV conjugated polymers with 1D distributed feedback (DFB) resonators was investigated. The conjugated polymers were spin-coated onto substrates to form thin film waveguides. By photo pumping in a stripe area of the samples, ASE with in-plane wave propagation along the stripe was generated. 1D grating made of SU8 photoresist fabricated by holographic lithography was used as a 1D DFB resonator to lower the threshold of ASE. A decrease of ASE threshold by 10 fold was observed in the MEH-PPV polymer, as well as a decrease of the spontaneous emission lifetime. The SU8 grating layer also acts as an out-coupler to transform the in-plane emission from conjugated polymers into out-of-plane emission. Hybrid white light emitters by spin-coating organic yellow emitting materials onto GaN-based blue light emitting diodes (LEDs) are also presented. F8BT polymer and aggregation induced emission (AIE) molecule BTPETD were used to form the down conversion cap layer separately. The resulting hybrid devices produce white light emissions with CIE coordinates (0.33,0.33) for F8BT polymer and (0.31,0.34) for BTPETD molecule respectively. The organic cap layer helps to extract electroluminance (EL) from GaN-based LEDs, while the rough surface of the BTPETD film scatters the light out of the device even more, as a result of these two factors, emissions with high luminance intensities were achieved for both devices, with for 3.6 x 104 cd/cm2 for F8BT and 1.4 x 105 cd/cm2 for BTPETD at drive current I=30mA. Silica oil was used to isolate the organic materials from air, an improvement of the device stability was observed.
Note Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2011
Language English
Format Thesis
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