高效柔性叠层有机太阳电池的中间连接层构筑及载流子复合机理研究

Tandem configuration is a promising approach to improve the organic solar cell performance by tackling the main losses in single junction organic solar cells, such as narrow absorption window and thermalization losses. In addition to the selection of novel pair of absorbers in different sub-cells, the choice of interfacial materials for constructing the interconnecting layer is also very critical for making high performance tandem organic solar cells. In this project, we are aiming at using n-type doping to obtained thickness insensitive electron transport materials with different conductivity to construct interconnecting layer in tandem organic solar cells. The thick interconnecting layer can protect the bottom active layer from being destroyed by top active layer solution. With reported high performance large band-gap and low band-gap organic solar cell materials as active layer, tandem organic solar cell will be fabricated. In there, the charge transport and recombination behavior will be carefully studied, the threshold value of conductivity for an ideal interconnecting layer will also be measured. After that, flexible transparent electrode with different geometry structures will be designed with the help of circuit simulation. The wettability of organic solution on the transparent electrode will be studied, and flexible tandem organic solar cell based on developed configuration will be fabricated on the designed flexible electrode. At last, large area tandem organic solar cell by using roll-to-roll processing will be realized. The parameters to deposit each layer and its impact on the underneath layer will be investigated. This project will deliver the mechanism and method to prepare high performance flexible tandem organic solar cells, and preliminarily reveal the feasibility of fabricating large area tandem organic solar cell by using roll-to-roll processing.

叠层结构的有机太阳电池因可以更加全面的利用太阳光子的能量，因而更有利于获得高效的电池器件。其中，中间连接层的构筑是成功获得叠层器件的关键之一。本项目旨在利用n型掺杂获得具有不同电导率的电子传输材料以构筑具有理想载流子复合特性的中间连接层。以光谱匹配的宽、窄带隙有机太阳电池材料为活性层构筑叠层太阳电池器件，研究高电导率薄膜在中间连接层中的关键作用及中间连接层中激子的复合过程。对器件各层建立光学模型进行逐步、协同优化以提高光子吸收、载流子复合与传输、电荷收集，实现溶液加工高效叠层有机太阳电池器件；其次，设计具有高透光率和高导电性的透明柔性电极，在已开发的叠层电池基础上实现溶液加工的高效柔性叠层有机太阳电池器件；最后尝试将开发的高效柔性叠层有机太阳电池器件通过卷对卷设备进行加工以期获得高效的大面积器件，为有机太阳电池的商业化应用提供理论依据和实践经验。

本项目拟构筑基于n型掺杂的有机/有机结构中间连接层并用于高效叠层有机太阳电池的制备。研究不同掺杂方式、掺杂强度对电子传输材料的载流子浓度、陷阱态密度、能级漂移、电导率和溶液加工性能的影响，获得可溶液加工的具有不同稳定掺杂态的电子传输材料；研究不同掺杂态中间连接层中载流子复合的微观电子过程，并外推出极限情况下载流子的复合行为；将掺杂后的电子传输材料应用到卷对卷加工工艺中实现大面积叠层有机太阳电池的制备。.围绕这些研究目标，本项目开展了以下研究内容，并取得了多项研究成果：构筑了一系列具有代表性的叠层有机太阳电池中间连接层结构，实现了可印刷加工中间连接层以及柔性叠层有机太阳电池；研究了中间层中载流子的复合行为，结果发现载流子的非平衡复合将会导致器件中载流子的积累，从而导致器件性能大幅下降；基于这些中间连接层，构筑了一系列高效叠层器件以及高开路电压叠层器件。