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High Light Outcoupling Efficiency from Periodically Corrugated OLEDs
ACS Omega ( IF 3.7 ) Pub Date : 2021-03-23 , DOI: 10.1021/acsomega.1c00903
Yu Zhang 1 , Rana Biswas 1, 2
Affiliation  

Organic light-emitting diodes (OLEDs) suffer from poor light outcoupling efficiency (ηout < 20%) due to large internal waveguiding in the high-index layers/substrate, and plasmonic losses at the metal cathode interface. A promising approach to enhance light outcoupling is to utilize internal periodic corrugations that can diffract waveguided and plasmonic modes back to the air cone. Although corrugations can strongly diffract trapped modes, the optimal geometry of corrugations and limits to ηout are not well-established. We develop a general rigorous scattering matrix theory for light emission from corrugated OLEDs, by solving Maxwell’s equations in Fourier space, incorporating the environment-induced modification of the optical emission rate (Purcell effect). We computationally obtain the spectrally emissive power inside and outside the OLED. We find conformally corrugated OLEDs, where all OLED interfaces are conformal with a photonic crystal substrate, having triangular lattice symmetry, exhibit high light outcoupling ηout ∼60–65%, and an enhancement factor exceeding 3 for optimal pitch values between 1 and 2.5 μm. Waveguided and surface plasmon modes are strongly diffracted to the air cone through first-order diffraction. ηout is insensitive to corrugation heights larger than 100 nm. There is a gradual roll-off in ηout for a larger pitch and sharper decreases for small pitch values. Plasmonic losses remain below 10% for all corrugation pitch values. Our predicted OLED designs provide a pathway for achieving very high light outcoupling over the full optical spectrum that can advance organic optoelectronic science and solid-state lighting.

中文翻译:


周期性波纹 OLED 的高光输出耦合效率



由于高折射率层/基板中的大内部波导以及金属阴极界面处的等离子体损耗,有机发光二极管 (OLED) 的光输出耦合效率较差 (η out < 20%)。增强光输出耦合的一种有前途的方法是利用内部周期性波纹,该波纹可以将波导和等离子体模式衍射回空气锥体。尽管波纹可以强烈地衍射俘获模式,但波纹的最佳几何形状和 η out的限制尚未确定。我们通过求解傅立叶空间中的麦克斯韦方程,并结合环境引起的光发射率修改(珀塞尔效应),开发了一种适用于波纹 OLED 光发射的通用严格散射矩阵理论。我们通过计算获得 OLED 内部和外部的光谱发射功率。我们发现共形波纹 OLED,其中所有 OLED 界面均与光子晶体基板共形,具有三角晶格对称性,表现出高光输出耦合 η out ~60–65%,并且对于 1 至 2.5 μm 之间的最佳节距值,增强因子超过 3 。波导和表面等离子体激元模式通过一级衍射强烈衍射到空气锥体。 η out对大于 100 nm 的波纹高度不敏感。对于较大的螺距值,η out会逐渐滚降,而对于较小的螺距值,则 η out 会急剧下降。所有波纹节距值的等离激元损失均低于 10%。我们预测的 OLED 设计提供了一条在整个光谱范围内实现非常高的光输出耦合的途径,从而推动有机光电科学和固态照明的发展。
更新日期:2021-04-06
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