Lateral radiation of the substrate of electrically pumped organic light-emitting diodes
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摘要:
有机发光二极管衬底侧向辐射光谱与正向辐射光谱相比，存在明显的窄化现象。研究影响器件侧向辐射光谱窄化的因素，进一步减小辐射光谱的线宽，可为电泵浦有机发光二极管 辐射研究打下基础。本文研究了随有机发光二极管空穴传输层 NPB 厚度的变化，器件衬底侧向辐射光谱的半高宽、峰位以及偏振特性的变化情况。比较了有机发光二极管衬底边缘两侧蒸镀银膜与未蒸镀银膜时的衬底侧向辐射光谱。研究发现蒸镀银膜时有机发光二极管的衬底侧向辐射光谱半高宽变窄，并且当空穴传输层 NPB 的厚度为 130 nm 时，器件衬底侧向辐射光谱半高宽低至 14 nm。说明器件衬底两侧存在银膜作为反射镜的情况下，衬底中侧向传播的光将受到光学谐振腔的作用。本文的研究结果为有机发光二极管辐射光谱的窄化和辐射光放大提供了一种新思路。
Abstract:There is a significant narrowing of the lateral radiation spectrum of the substrate of organic light-emitting diodes as compared to the forward radiation spectrum. Studying the factors that affect the lateral radiation spectrum narrowing of the device and further reducing the spectral linewidth can provide a foundation for the study of the electrically pumped organic light-emitting diode laser radiation. We study the full width at half maximum, peak wavelength, and polarization characteristics of lateral radiation spectrum in organic light-emitting diode substrate, with the thickness changes of hole transport layer NPB. The lateral radiation spectra of organic light-emitting diode with Ag film evaporated on both sides of the substrate edge are compared with those of organic light-emitting diode without Ag film. The full width at half maximum of the lateral radiation spectrum with Ag film is narrower. When the NPB thickness is 130 nm, the full width at half maximum of the lateral radiation spectrum in the device substrate reaches its narrowest, which is 14 nm. This shows that the optical resonator will affect the light propagating laterally in an organic light-emitting diode substrate when mirrors are provided on both edge sides of the substrate. The results indicate new approaches to narrowing the radiation spectrum and amplifying the light of organic light-emitting diodes.
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图 3 不同厚度Ag、Al膜反射率随波长变化情况
Figure 3. Reflectances of Ag and Al films with different thicknesses varying with wavelength
图 4 电致发光光谱采集系统结构图
Figure 4. Structural diagram of the electroluminescence spectrum collection system
图 5 NPB 厚度在45~300 nm 范围内的辐射光谱
Figure 5. Radiation spectra when NPB thickness is in the range of 45~300 nm
图 6 OLED 衬底侧向辐射光谱的偏振特性
Figure 6. Polarization characteristics of lateral radiation spectrum of the OLED substrate
图 7 NPB 厚度在45~300 nm 范围内 OLED 的侧向发射光谱
Figure 7. Lateral emission spectra from OLED when the NPB thickness is in the range of 45−300 nm
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