基于静电喷雾的聚合物太阳能电池活性层微观结构调控与光电性能研究

Despite the rapid progress in polymer solar cells, a few key research issues remain to be solved. Fundamentally, the active layer structure needs to be optimized to further improve the device efficiency; practically, the manufacturing technique should be scalable and compatible to roll-to-roll process.. The morphology of the active layer in polymer solar cells is critical to the device performance. Currently the most popular configuration is based on the bulk heterojunction (BHJ) matrix of donor and acceptor materials. Although BHJ benefits efficient separation of excitons, the collection of charge carriers are incomplete due to numerous random dead ends in the matrix. A promising pathway to more efficient photovoltaic devices is to construct active layers structure that offers efficient exciton separation as well as complete charge carrier collection. To that end, this project proposes to use electrospray method to fabricate, control, and fine-tune the nanostructure of the active layers of the polymer solar cells. Electrospray is a versatile approach that enables us to construct ordered interpenetration network of donor/accepter materials, change the donor/accepter concentration gradient along the vertical direction, and re-adjust the molecular orientation of the polymer. The project aims to study the interplay between detailed active layer morphology and the photoelectric properties such as the light absorption, exciton dissociation, and charge carrier transport/collection. Devices will be fabricated and characterized based on the optimized active layer structure. This project is expected to lay both theoretical and experimental foundation for more efficient polymer solar cells.

聚合物太阳能电池近年来发展迅速，但仍有若干关键问题急需解决：从基础研究角度，应进一步改善活性层结构来提高其效率；从应用角度，制作工艺需适应卷对卷生产的要求。. 活性层形貌是影响聚合物太阳能电池性能的关键因素。当前普遍采用的活性层结构是体异质结，这种活性层结构有利于激子解离，然而对于载流子的传输和收集并不理想。构筑具有理想形貌的活性层是进一步改善器件效率的有效途径。本项目拟采用静电喷雾作为制备方法，研究对聚合物太阳能电池活性层微观结构的调控。通过控制静电喷雾工艺参数，构筑有序的给体／受体互穿网络、调节给体和受体材料在垂直于基板方向的浓度分布、调控聚合物分子取向。研究具有不同微观结构的活性层光吸收、激子解离和载流子传输过程，深入理解活性层形貌结构与光电性能之间的关系。在此基础上获得具有理想形貌结构的活性层，制备出高效率聚合物太阳能电池，为有机太阳能电池的发展提供理论和实验依据。

近年来，有机光伏材料发展迅速，尤其是非富勒烯受体材料的出现，使有机光伏电池的光电转换效率不断刷新，成为令人瞩目的新型可再生能源。然而要实现产业化，有机光伏电池仍然面临亟待解决的挑战，主要包括：共混结构的体异质结活性层形貌对于载流子的传输和收集并不理想，同时稳定性和可控性不好；能够兼顾器件效率和适用于大面积生产的有机柔性薄膜制备工艺仍有待开发。本项目的研究从活性层形貌和制备工艺两方面，为解决有机光伏电池产业化生产面临的瓶颈问题做出贡献。基于静电喷雾法构筑理想形貌的活性层，研究了形貌调控机理，深入分析活性层微观结构与器件光电性能之间的关系，从而实现制备高效的有机光伏电池。同时，基于静电喷雾法打印制备了非富勒烯受体的有机光伏活性层以及钙钛矿光伏活性层，均获得了高效率电池器件。本项目构筑的活性层结构与共混体异质结相比，制备的可控性和重复性高、性质稳定，更适合大面积生产，从而为有机光伏电池的产业化生产带来新的机遇。本项目所研究的静电喷雾法在有机和钙钛矿薄膜制备方面具有普适性，也适用于有机场效应管、有机/钙钛矿发光二极管等有机电子器件的功能层薄膜制备和性能优化，可为印刷法制造高性能柔性电子器件提供新的工艺方法和研究思路。