The Optical Constants of Solution-Processed Semiconductors-New Challenges with Perovskites and Non-Fullerene Acceptors
The Optical Constants of Solution-Processed Semiconductors-New Challenges with Perovskites and Non-Fullerene Acceptors
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DOI：
10.1002/adom.202000319
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发表时间：
2020-05-27
影响因子：
9
通讯作者：
Armin, Ardalan
中科院分区：
文献类型：
--
作者：
Kerremans, Robin;Kaiser, Christina;Armin, Ardalan
固体薄膜光学常数的精确测定是光电子学及其相关领域几十年来一直在努力的奋进。这些常数，即折射率和消光（或衰减）系数，是决定电磁场在任何介质中传播的基本材料特性。它们形成了成熟模型的输入，这些模型允许设计和优化多层堆叠结构，如薄膜太阳能电池、发光二极管和光电探测器。这些测定对于散射和高度吸收的材料特别具有挑战性。在这项工作中，一种新的和资源有效的方法，用于光学常数测定的基础上结合迭代，反向传输矩阵模型和Kramers-Kronig关系的透射分光光度法的报告。该方法是使用更传统的椭圆偏振法验证一些功能上重要的半导体，包括最近出现的有机非富勒烯电子受体（NFA）和钙钛矿的光学常数在紫外-可见-近红外区域提供。值得注意的是，NFA被发现呈现出非常高的折射率和消光系数，预测这些折射率和消光系数对新的记录效率有机太阳能电池的腔电光学具有深远的影响，其中NFA是新的记录效率有机太阳能电池的关键部件。
Accurate determination of the optical constants of thin film solids has been an ongoing endeavor in optoelectronics and related fields for decades. These constants, namely the refractive index and extinction (or attenuation) coefficient, are the fundamental material properties that dictate electromagnetic field propagation in any medium. They form the inputs to well-established models that allow for design and optimization of multilayer stack structures such as thin film solar cells, light-emitting diodes, and photodetectors. These determinations are particularly challenging for materials that are scattering and highly absorbing. In this work, a new and resource-efficient approach for optical constant determination based upon transmission spectrophotometry in combination with an iterative, reverse transfer matrix model and the Kramers-Kronig relation is reported. The approach is validated using more conventional ellipsometry for a number of functionally important semiconductors, including the recently emergent organic non-fullerene electron acceptors (NFAs) and perovskites for which the optical constants in the UV-vis-near IR region are provided. Notably, the NFAs are found to present anomalously high refractive indices and extinction coefficients that are predicted to have a profound influence on the cavity electro-optics of the new record efficiency organic solar cells of which they are key components.