Study of Electroluminescent Property of Organic Slab Waveguide Device

• Main Authors: Yu-syuan Huang, 黃裕軒
• Other Authors: Jui-fen Chang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/6c2sbd

碩士 === 國立中央大學 === 照明與顯示科技研究所 === 102 === In this thesis, we used a polymer material, PVK (Poly(9-vinylcarbazole)), as the spacer and a fluorescent small molecule, BSB-Cz (4,4’-bis[(N-carbazole) styryl] biphenyl), as the emission layer to fabricate the organic multilayer slab waveguide device, and investigated the electroluminescent properties of the device driven with high current density. First, we optimized the electrically property of devices by varying the thickness of PVK. The best performance was obtained with 100 nm thick PVK. After then, we fixed the PVK thickness at 100 nm and changed the thickness of emission layer (BSB-Cz). For 250-260 nm thick BSB-Cz the cutoff wavelength measured from the side emission spectrum was found to coincide with the 0-1 vibronic peak of BSB-Cz, which corresponds to the regime of the highest gain coefficient. Finally, we fixed the thickness of 100 nm for PVK and 250 nm or 260 nm for BSB-Cz and used pulse bias to drive the device with high energy. The variation of side emission intensity against pump energy was investigated. We observed that such a slab waveguide device could exhibit stable emission efficiency when driving with high current density. In general, the devices show a linear growth of the side emission versus pump energy without apparent emission roll-off phenomenon as the current density exceeds 1 A/cm2. Intriguingly, in some exceptional devices with superior emission property, we observed light amplification-like phenomena. We believe that with further optimization of the electrical properties and measurement conditions, the electrically pumped ASE phenomenon can be demonstrated.