Pfeiffer Pascal, Stümmler Dominik, Sanders Simon, Beckmann Carsten, Simkus Gintautas, Heuken Michael, Vescan Andrei, Kalisch Holger
Compound Semiconductor Technology, RWTH Aachen University, Sommerfeldstr. 18, 52074 Aachen, Germany.
J Nanosci Nanotechnol. 2019 Jul 1;19(7):3959-3963. doi: 10.1166/jnn.2019.16306.
In this work, we use the transfer matrix method to optimize TPBi capping layers deposited on organic light emitting diodes with respect to light extraction and transmittance. The green transparent organic light emitting diodes comprise three organic semiconductors (CBP, Ir(ppy)₃ and TPBi) forming an efficient simplified phosphorescent organic light emitting diode stack. A transparent cathode of 2 nm Cs₂CO₃, 2 nm Al and 16 nm Au is deposited by thermal evaporation. The diode stack as well as the capping layer are deposited by organic vapor phase deposition. The refractive indices and extinction coefficients of all materials in the transparent organic light emitting diodes (glass, indium tin oxide, organic semiconductors and cathode) are determined using spectroscopic ellipsometry combined with optical transmittance and reflectance measurements. With these spectrally resolved data, we calculate the transmittance of transparent organic light emitting diodes with TPBi capping layers of different thicknesses. The results were validated with high accuracy in the visible spectral range and beyond (360 nm-1000 nm) by a series of experiments. By choosing a TPBi capping layer of optimized thickness (here 50 nm), we fabricated transparent organic light emitting diodes with an optical transmittance which was strongly enhanced from 47% (reference without capping layer) to 65%, measured at 555 nm.
在这项工作中，我们使用转移矩阵法来优化沉积在有机发光二极管上的TPBi覆盖层的光提取和透射率。绿色透明有机发光二极管由三种有机半导体（CBP、Ir(ppy)₃和TPBi）组成，形成一个高效的简化磷光有机发光二极管堆叠结构。通过热蒸发沉积2nm Cs₂CO₃、2nm Al和16nm Au的透明阴极。二极管堆叠结构以及覆盖层通过有机气相沉积法沉积。使用光谱椭偏仪结合光学透射率和反射率测量来确定透明有机发光二极管（玻璃、氧化铟锡、有机半导体和阴极）中所有材料的折射率和消光系数。利用这些光谱分辨数据，我们计算了具有不同厚度TPBi覆盖层的透明有机发光二极管的透射率。通过一系列实验，在可见光谱范围及以外（360nm - 1000nm）内对结果进行了高精度验证。通过选择优化厚度（此处为50nm）的TPBi覆盖层，我们制备了透明有机发光二极管，其在555nm处测量的光学透射率从47%（无覆盖层的参考值）大幅提高到了65%。
