Energy Frontier Research Center for Excitonics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science. 2013 Apr 19;340(6130):334-7. doi: 10.1126/science.1232994.
Singlet exciton fission transforms a molecular singlet excited state into two triplet states, each with half the energy of the original singlet. In solar cells, it could potentially double the photocurrent from high-energy photons. We demonstrate organic solar cells that exploit singlet exciton fission in pentacene to generate more than one electron per incident photon in a portion of the visible spectrum. Using a fullerene acceptor, a poly(3-hexylthiophene) exciton confinement layer, and a conventional optical trapping scheme, we show a peak external quantum efficiency of (109 ± 1)% at wavelength λ = 670 nanometers for a 15-nanometer-thick pentacene film. The corresponding internal quantum efficiency is (160 ± 10)%. Analysis of the magnetic field effect on photocurrent suggests that the triplet yield approaches 200% for pentacene films thicker than 5 nanometers.
单线态激子裂变将一个分子的单线态激发态转化为两个三线态态，每个态的能量都为原始单线态的一半。在太阳能电池中，它有可能将高能光子的光电流增加一倍。我们展示了一种有机太阳能电池，该电池利用并五苯中的单线态激子裂变在可见光谱的一部分中产生每个入射光子的多个电子。使用富勒烯受体、聚(3-己基噻吩)激子限制层和传统的光学俘获方案，我们在 15 纳米厚的并五苯薄膜的 λ = 670 纳米处获得了高达 (109 ± 1)%的峰值外量子效率。相应的内量子效率为 (160 ± 10)%。对光电流的磁场效应的分析表明，对于厚度超过 5 纳米的并五苯薄膜，三线态产率接近 200%。
