Kolb Florian, El Gemayel Mirella, Khan Imran, Dostalek Jakub, Trattnig Roman, Sommer Christian, List-Kratochvil Emil J W
Institute of Surface Technologies and Photonics, Joanneum Research Forschungsges. mbH, Franz-Pichler-Straße 30, 8160 Weiz, Austria.
AIT-Austrian Institute of Technology GmbH, BioSensor Technologies, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
Appl Phys A Mater Sci Process. 2023;129(3):230. doi: 10.1007/s00339-023-06492-6. Epub 2023 Mar 2.
Nano-patterning the semiconducting photoactive layer/back electrode interface of organic photovoltaic devices is a widely accepted approach to enhance the power conversion efficiency through the exploitation of numerous photonic and plasmonic effects. Yet, nano-patterning the semiconductor/metal interface leads to intertwined effects that impact the optical as well as the electrical characteristic of solar cells. In this work we aim to disentangle the optical and electrical effects of a nano-structured semiconductor/metal interface on the device performance. For this, we use an inverted bulk heterojunction P3HT:PCBM solar cell structure, where the nano-patterned photoactive layer/back electrode interface is realized by patterning the active layer with sinusoidal grating profiles bearing a periodicity of 300 nm or 400 nm through imprint lithography while varying the photoactive layer thickness (L ) between 90 and 400 nm. The optical and electrical device characteristics of nano-patterned solar cells are compared to the characteristics of control devices, featuring a planar photoactive layer/back electrode interface. We find that patterned solar cells show for an enhanced photocurrent generation for a L above 284 nm, which is not observed when using thinner active layer thicknesses. Simulating the optical characteristic of planar and patterned devices through a finite-difference time-domain approach proves for an increased light absorption in presence of a patterned electrode interface, originating from the excitation of propagating surface plasmon and dielectric waveguide modes. Evaluation of the external quantum efficiency characteristic and the voltage dependent charge extraction characteristics of fabricated planar and patterned solar cells reveals, however, that the increased photocurrents of patterned devices do not stem from an optical enhancement but from an improved charge carrier extraction efficiency in the space charge limited extraction regime. Presented findings clearly demonstrate that the improved charge extraction efficiency of patterned solar cells is linked to the periodic surface corrugation of the (back) electrode interface.
The online version contains supplementary material available at 10.1007/s00339-023-06492-6.
对有机光伏器件的半导体光活性层/背电极界面进行纳米图案化是一种广泛认可的方法，可通过利用多种光子和等离子体效应来提高功率转换效率。然而，对半导体/金属界面进行纳米图案化会导致相互交织的效应，从而影响太阳能电池的光学和电学特性。在这项工作中，我们旨在厘清纳米结构的半导体/金属界面对器件性能的光学和电学效应。为此，我们使用了一种倒置体异质结P3HT:PCBM太阳能电池结构，其中通过压印光刻技术对有源层进行图案化，使其具有周期为300纳米或400纳米的正弦光栅轮廓，从而实现纳米图案化的光活性层/背电极界面，同时将光活性层厚度（L）在90至400纳米之间变化。将纳米图案化太阳能电池的光学和电学器件特性与具有平面光活性层/背电极界面的对照器件的特性进行比较。我们发现，对于厚度L大于284纳米的情况，图案化太阳能电池的光电流产生增强，而在使用较薄有源层厚度时未观察到这种情况。通过时域有限差分法模拟平面和图案化器件的光学特性表明，在存在图案化电极界面的情况下，光吸收增加，这源于传播表面等离子体和介质波导模式的激发。然而，对制造的平面和图案化太阳能电池的外部量子效率特性以及电压依赖性电荷提取特性的评估表明，图案化器件光电流的增加并非源于光学增强，而是源于空间电荷限制提取区域中电荷载流子提取效率的提高。呈现的研究结果清楚地表明，图案化太阳能电池电荷提取效率的提高与（背）电极界面的周期性表面波纹有关。
在线版本包含可在10.1007/s00339-023-06492-6获取的补充材料。
