| 摘要: | 本論文利用有機小分子螢光材料BSB-Cz(4,4’-bis[(N-carbazole) styryl] biphenyl)高折射率且雙軸特性的為發光層材料匹配低折射率PVK(Poly(9-vinylcarbazole))製作非等向性平板波導之OLED元件。我們參考前研究已優化之PVK 厚度及BSB-Cz 厚度，在此使用100 nm 的 PVK 有較佳的光電特性表現及270 nm的BSB-Cz，此為光增益係數最高之波段。我們鍍製不同電子注入層分析其光電特性、EL(電致發光)及PL(光致發光)頻譜之差異。我們得到MoO3與Li2CO3 的組合比PEDOT:PSS與LiF的組合能夠有效降低元件之開路電壓，約從35V下降至25V，雖然整體外部量子效應(EQE%)的結果差不多，但在相同電壓(40V)下MoO3與Li2CO3 的組合在光強與電流的表現較佳。我們也透過空間頻譜量測觀察到這種波導式的OLED有非等向性的光譜分布，觀察到隨著高角度有些微藍移的趨勢。
我們進一步觀察元件內部之等效折射率及波導模態的光場分佈，方法是利用玻璃基板與BSB-Cz中間插入PVK，利用PVK的厚度(0、50、100、150與200 nm)變化來觀察等效折射率之變化，我們發現在100 nm以上之PVK會減少玻璃基板對PVK以下整體等效折射率的影響，使PVK以下整體的等效折射率從1.46提升至1.67越為接近PVK本身之折射率(1.6 ~ 1.7)，且發現PVK 的厚度改變可以改變波導模態的光場分布。接著，我們再利用此論文所使用之元件結構觀察波導模態的光場分布，我們製備此元件(玻璃基板/ITO/MoO3/PVK/BSB-Cz)並蓋上四種不同上介質(Air；Ag； LiF/ Ag ；Li2CO3/ Ag)，侷限因子從 86.05% 提升至90.81%，可以觀察到Li2CO3/ Ag能顯著的改善讓光子侷限在有機層裡面，使得發光效能更為優化。
;In this thesis, the high refractive index and biaxial properties of the organic small molecule fluorescent material BSB-Cz (4,4′-bis[(N-carbazole) styryl] biphenyl) are used to match the low refractive index PVK (Poly (9) -vinylcarbazole)) An OLED element for making an anisotropic slab waveguide. We refer to the optimized PVK thickness and BSB-Cz thickness of the previous study. Here, the 100 nm PVK has better photoelectric characteristics and 270 nm BSB-Cz, which is the band with the highest optical gain coefficient. We plated different electron injection layers to analyze the differences in their photoelectric properties, EL (electroluminescence) and PL (photoluminescence) spectra. We get a combination of MoO3 and Li2CO3 than PEDOT: PSS and LiF can effectively reduce the open circuit voltage of the component, which is reduced from 35V to 25V, although the overall external quantum effect (EQE%) results almost the same, but at the same voltage (40V) The combination of MoO3 and Li2CO3 performs better in light intensity and current. We also observed the non-isotropic spectral distribution of this waveguide-type OLED through spatial spectrum measurement, and observed a slight blue-shift trend with high angle.
We further observed the equivalent refractive index inside the component and the optical field distribution of the waveguide mode by inserting PVK between the glass substrate and BSB-Cz, using the thickness of PVK (0, 50, 100, 150 and 200 nm). Observing the change of the equivalent refractive index, we found that PVK above 100 nm will reduce the effect of the glass substrate on the overall equivalent refractive index below PVK, so that the overall equivalent refractive index below PVK is raised from 1.46 to 1.67, which is closer to PVK itself. The refractive index (1.6 ~ 1.7), and found that the thickness of the PVK changes can change the light field distribution of the waveguide mode. Next, we use the component structure used in this paper to observe the light field distribution of the waveguide mode. We prepare this component (glass substrate/ITO/MoO3/PVK/BSB-Cz) and cover it with four different upper media (Air; Ag; LiF/Ag; Li2CO3/Ag), the localization factor increased from 86.05% to 90.81%. It can be observed that Li2CO3/Ag can significantly improve the photon confinement in the organic layer, which makes the luminous efficiency more optimized. |
