聚NDI2OD-T2的兴奋状态寿命本质上是短暂的
Melissa K Gish1, Chamikara D Karunasena2, Joshua M Carr3
1Materials, Chemical, and Computational Science Directorate, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
概括
结合聚合物如聚NDI2OD-T2 (N2200) 由于其固有的分子特性而不是聚合而显示出短暂的激发状态寿命. 这一发现影响有机太阳能电池材料设计.
科学领域:
- 材料科学 材料科学 材料科学
- 太阳能光伏发电是如何实现的
- 有机电子 有机电子
背景情况:
- 结合聚合物与捐赠者-接受者细分是有机太阳能电池的关键,因为近红外吸收.
- 聚NDI2OD-T2 (N2200) 是一种常见的接受电子的材料,但其光电贡献有限,激发状态寿命短.
- N2200的短激发状态寿命通常归因于聚合,阻碍了有效的电荷生成.
研究的目的:
- 确定聚NDI2OD-T2 (N2200) 的短激发状态寿命是其骨干结构的内在性质还是聚合的外在效应.
- 将N2200的光物理与模型化合物进行比较,以了解基本的光物理限制.
主要方法:
- 过渡吸收光谱学被用来研究N2200和模拟化合物 (NDI-T2-NDI,T2-NDI-T2) 在稀释溶液中的兴奋状态动态.
- 进行了电子结构计算,以分析激发状态属性和衰变路径.
主要成果:
- 在溶液中分子分离的模型化合物表现出比N2200聚合物 (133 ps) 更快的基态恢复动力学 (27-45 ps).
- 在聚合物和模型化合物中,最低的激发状态具有比西奥芬 (T2) 到二胺 (NDI) 电荷转移 (CT) 特性.
- 计算显示,快速的非辐射衰变到基态 (GS) 是由CT和GS状态之间的强电子合驱动的,加上强的电子振动合.
结论:
- N2200的短激发状态寿命是其分子结构的内在特征,不仅仅是由于聚合.
- 快速的非辐射衰变途径限制了这些推拉合聚合物的效率在光电子应用中.
- 了解这些内在的局限性对于设计下一代有机太阳能电池材料以提高性能至关重要.
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