Ullbrich Sascha, Benduhn Johannes, Jia Xiangkun, Nikolis Vasileios C, Tvingstedt Kristofer, Piersimoni Fortunato, Roland Steffen, Liu Yuan, Wu Jinhan, Fischer Axel, Neher Dieter, Reineke Sebastian, Spoltore Donato, Vandewal Koen
Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Dresden, Germany.
Experimental Physics VI, Julius-Maximilian University of Würzburg, Würzburg, Germany.
Nat Mater. 2019 May;18(5):459-464. doi: 10.1038/s41563-019-0324-5. Epub 2019 Apr 1.
Intermolecular charge-transfer states at the interface between electron donating (D) and accepting (A) materials are crucial for the operation of organic solar cells but can also be exploited for organic light-emitting diodes. Non-radiative charge-transfer state decay is dominant in state-of-the-art D-A-based organic solar cells and is responsible for large voltage losses and relatively low power-conversion efficiencies as well as electroluminescence external quantum yields in the 0.01-0.0001% range. In contrast, the electroluminescence external quantum yield reaches up to 16% in D-A-based organic light-emitting diodes. Here, we show that proper control of charge-transfer state properties allows simultaneous occurrence of a high photovoltaic and emission quantum yield within a single, visible-light-emitting D-A system. This leads to ultralow-emission turn-on voltages as well as significantly reduced voltage losses upon solar illumination. These results unify the description of the electro-optical properties of charge-transfer states in organic optoelectronic devices and foster the use of organic D-A blends in energy conversion applications involving visible and ultraviolet photons.
供体（D）材料与受体（A）材料界面处的分子间电荷转移态对于有机太阳能电池的运行至关重要，但也可用于有机发光二极管。在基于D-A的先进有机太阳能电池中，非辐射电荷转移态衰减占主导，这导致了较大的电压损失、相对较低的功率转换效率以及0.01 - 0.0001%范围内的电致发光外量子产率。相比之下，基于D-A的有机发光二极管中的电致发光外量子产率可达16%。在此，我们表明，对电荷转移态性质的适当控制能够使单一的可见光发射D-A系统同时实现高光伏量子产率和发射量子产率。这导致了超低的发光开启电压以及在太阳光照下显著降低的电压损失。这些结果统一了有机光电器件中电荷转移态电光性质的描述，并促进了有机D-A混合物在涉及可见光和紫外光子的能量转换应用中的使用。
