Shivhare Rishi, Banerji Natalie
Dept. für Chemie, Biochemie und Pharmazie, University of Bern, Freiestrasse 3, CH-3012 Bern.
Dept. für Chemie, Biochemie und Pharmazie, University of Bern, Freiestrasse 3, CH-3012 Bern;, Email:
Chimia (Aarau). 2021 Oct 27;75(10):862-867. doi: 10.2533/chimia.2021.862.
The power conversion efficiency of organic solar cells has seen a huge improvement in recent years with state-of-the-art solar cells showcasing efficiencies of ∼18.5 %, which is approaching the performance of inorganic and hybrid-perovskite solar cell technologies. This improvement can be mainly attributed to the discovery of highly efficient donor:acceptor blends with a near-zero energetic offset between the molecular orbital levels of the donor and the acceptor component. A distinctive feature of the high efficiency, low energy-offset blends is that they exhibit a concomitant increase in the short-circuit density and the open-circuit voltage of the solar cell. High open-circuit voltage results from the reduced photon energy loss in the exciton dissociation step, while a high short-circuit current density can be attributed to an efficient charge generation process. The reasons for the efficient exciton dissociation and subsequent separation of Coulomb bound electron-hole pair at negligible driving force is not well understood and, in this short review, we highlight recent results which shed light on the mechanism of charge generation in low energy-offset blends.
近年来，有机太阳能电池的功率转换效率有了巨大提升，最先进的太阳能电池展示出了约18.5%的效率，这已接近无机和混合钙钛矿太阳能电池技术的性能。这种提升主要归功于高效供体 - 受体共混物的发现，其供体和受体组分的分子轨道能级之间的能量差近乎为零。高效、低能量差共混物的一个显著特征是，它们会使太阳能电池的短路密度和开路电压同时增加。高开路电压源于激子解离步骤中光子能量损失的减少，而高短路电流密度可归因于高效的电荷产生过程。在可忽略的驱动力下，激子高效解离以及随后库仑束缚电子 - 空穴对分离的原因尚未完全理解，在这篇简短的综述中，我们重点介绍了近期的研究结果，这些结果揭示了低能量差共混物中电荷产生的机制。
