聚合物太阳能电池中双面微纳陷光结构的研究

Light trapping is one of the most important approaches to improve the power conversion efficiency of solar cells. Compare with the silicon-based solar cells, the design and application of light trapping structures are highly challenging due to the thinner active layer in polymer solar cells. Considering the different features between interior and exterior of solar cells, this project will prepare the dual-sided micro- and nano- combined structures based on sol-gel method assisted by nano-imprinting technique, by which the effects of the structures on light coupling, propagation and carrier transport are investigated. The studied micro- and nano- combined structures outside the solar cells have large feature size for antireflection and light trapping, giving rise to enhance light transmission and change light propagation preliminarily. Inside the solar cells, the small feature sized structure might have influences on light field distribution in organic functional layer, which will be studied by the theoretically simulated calculation. And it will be studied that the effects of the interior structure on the carrier transport and collection in organic functional layers. This project will benefit the understanding of opto-electric combined process of polymer solar cells. The efforts will made on further improvement of conversion efficiency of polymer solar cells by exploring the “electrically thin” and “optically thick” light trapping structure. With the enhancement of the device power conversion efficiency, light trapping technology becomes an important approach to further improve the performance of those existed high efficiency polymer solar cells. This project will investigate the antireflection and light trapping effect of micro- and nano- combined structures with large scale to the incident light from the outside of the cell. The light in-coupling of the device enhanced as well as the propagation direction of incident light changed. Further, the light field distribution in organic functional layers affected by the inside micro- and nano- combined structures will be investigated by the theoretical simulated calculation, and we explained the carrier transportation and collection regulated by the organic functional layers with the transferred morphology from inside light trapping structures. This project demonstrates a new way to further recognize the physics between the light and electric transportation property in polymer solar cells, and realizes the light management technique used in the light trapping of polymer solar cells. Besides, this project provides a more comprehensive guidance to explore “Electronically thin” and “Optically thick” light trapping structures in polymer solar cells. This study might inspire a novel strategy for optical loss suppression and high efficient light harvesting in active layer in polymer solar cells, which would be of a great significance for light management research in polymer solar cells.

陷光结构在太阳电池领域是提高转换效率的重要手段，与硅基太阳电池相比，聚合物电池中活性层更薄，使陷光结构的设计与应用面临更大的挑战。针对电池外部和内部的不同特点，本项目将研究基于溶胶凝胶法结合纳米压印制备的双面微纳陷光结构对电池中入射光耦合、传播与电荷传输的作用。所研究的电池外部的微纳结构具有较大尺寸，对入射光进行减反与陷光，使电池初步获得增透效应并改变入射光的传播方向；聚合物电池内部的微纳结构尺寸较小，结合理论模拟计算研究光经过小尺寸微纳陷光结构后活性层中的光场强度分布，并从实验上阐明该结构对有机功能层中载流子传输的影响。通过上述研究，深入了解聚合物太阳电池中光、电传输特性相互制约的物理过程，探索通过 “电学薄”和“光学厚”的陷光结构，进一步提升聚合物太阳电池转换效率。该研究有望为聚合物太阳电池中的光损耗抑制以及活性层的高效光利用提供新的研究思路，对聚合物太阳电池的光管理研究具有重要意义。

陷光结构在太阳能电池领域是提高转换效率的重要手段，与硅基太阳电池相比，有机太阳电池中活性层更薄，使陷光结构的设计与应用面临更大的挑战。针对聚合物电池结构特点，本项目基于溶胶凝胶法结合纳米压印技术制备了单级、多级金字塔及娥眼结构的微纳陷光复合结构，研究了它们对电池入射光的耦合与传播作用。所研究的微纳结构尺寸在2-3 um之间，在可见光波段的平均透过高达97.7%，雾度超过99.0%，使电池获得增透效应并改变入射光的传播方向，实现对入射光的有效减反与陷光作用。通过COMSOL多物理场仿真模拟计算，证明了光经过微纳陷光结构进入电池后，电场能量密度增强。结合器件制备及光伏特性研究结果得出，三种微纳结构复合形式下，电池的光电流转换提升明显，电流密度相对提升高达7.15%，对应的光电转换效率相对提升为6.87%。通过上述研究，对聚合物太阳电池中光、电传输特性相互制约的物理过程有了深入认识，阐明了陷光结构对实现聚合物太阳电池 “电学薄” 和“光学厚”的作用机理。本项目研究有望为聚合物太阳电池中的光损耗抑制以及活性层的高效光利用提供新的研究思路，对聚合物太阳电池的光管理研究具有重要意义。