Bag Saientan, Friederich Pascal, Kondov Ivan, Wenzel Wolfgang
Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science (IISc), Bangalore, India.
Steinbuch Centre for Computing (SCC), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
Sci Rep. 2019 Aug 27;9(1):12424. doi: 10.1038/s41598-019-48877-9.
Recent progress in the improvement of organic solar cells lead to a power conversion efficiency to over 16%. One of the key factors for this improvement is a more favorable energy level alignment between donor and acceptor materials, which demonstrates that the properties of interfaces between donor and acceptor regions are of paramount importance. Recent investigations showed a significant dependence of the energy levels of organic semiconductors upon admixture of different materials, but its origin is presently not well understood. Here, we use multiscale simulation protocols to investigate the molecular origin of the mixing induced energy level shifts and show that electrostatic properties, in particular higher-order multipole moments and polarizability determine the strength of the effect. The findings of this study may guide future material-design efforts in order to improve device performance by systematic modification of molecular properties.
有机太阳能电池性能改进方面的最新进展使功率转换效率超过了16%。这一改进的关键因素之一是供体和受体材料之间更有利的能级排列，这表明供体和受体区域之间界面的性质至关重要。最近的研究表明，有机半导体的能级对不同材料的混合有显著依赖性，但其起源目前尚未完全理解。在此，我们使用多尺度模拟方法来研究混合诱导能级移动的分子起源，并表明静电性质，特别是高阶多极矩和极化率决定了这种效应的强度。这项研究的结果可能会指导未来的材料设计工作，以便通过系统地改变分子性质来提高器件性能。
