An Energy-Gap Law for Photocurrent Generation in Fullerene-based Organic Solar Cells – The Case of Low-Donor Content-Blends,Journal of the American Chemical Society

当前位置： X-MOL 学术 › J. Am. Chem. Soc. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

An Energy-Gap Law for Photocurrent Generation in Fullerene-based Organic Solar Cells – The Case of Low-Donor Content-Blends
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2019-01-08 , DOI: 10.1021/jacs.8b09820
Elisa Collado-Fregoso ₁ , Silvina N. Pugliese _{2,

3} , Mariusz Wojcik ₄ , Johannes Benduhn ₅ , Eyal Bar-Or ₁ , Lorena Perdigón Toro ₁ , Ulrich Hörmann ₁ , Donato Spoltore ₅ , Koen Vandewal ₆ , Justin M. Hodgkiss _{2,

3} , Dieter Neher ₁

Affiliation

The involvement of charge-transfer (CT) states in the photogeneration and recombination of charge carriers has been an important focus of study within the organic photovoltaic community. In this work, we investigate the molecular factors determining the mechanism of photocurrent generation in low-donor-content organic solar cells, where the active layer is composed of vacuum-deposited C60 and small amounts of organic donor molecules. We find a pronounced decline of all photovoltaic parameters with decreasing CT state energy. Using a combination of steady-state photocurrent measurements and time-delayed collection field experiments, we demonstrate that the power conversion efficiency, and more specifically, the fill factor of these devices, is mainly determined by the bias dependence of photocurrent generation. By combining these findings with the results from ultrafast transient absorption spectroscopy, we show that blends with small CT energies perform poorly because of an increased nonradiative CT state decay rate and that this decay obeys an energy-gap law. Our work challenges the common view that a large energy offset at the heterojunction and/or the presence of fullerene clusters guarantee efficient CT dissociation and rather indicates that charge generation benefits from high CT state energies through a slower decay to the ground state.

中文翻译：

基于富勒烯的有机太阳能电池中光电流产生的能隙定律——低供体含量混合物的案例

电荷转移 (CT) 状态在电荷载流子的光生和复合中的参与一直是有机光伏界研究的重要焦点。在这项工作中，我们研究了决定低供体含量有机太阳能电池中光电流产生机制的分子因素，其中活性层由真空沉积的 C60 和少量有机供体分子组成。我们发现所有光伏参数随着 CT 状态能量的降低而显着下降。结合稳态光电流测量和延时收集场实验，我们证明了功率转换效率，更具体地说，这些器件的填充因子主要由光电流产生的偏置依赖性决定。通过将这些发现与超快瞬态吸收光谱的结果相结合，我们表明，由于非辐射 CT 状态衰减率增加，并且这种衰减遵循能隙定律，因此具有小 CT 能量的混合物表现不佳。我们的工作挑战了普遍的观点，即异质结处的大能量偏移和/或富勒烯簇的存在保证了有效的 CT 解离，而是表明电荷生成受益于高 CT 状态能量通过较慢的衰减到基态。

更新日期：2019-01-08

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南