Mizokuro Toshiko, Tanigaki Nobutaka, Miyadera Tetsuhiko, Shibata Yousei, Koganezawa Tomoyuki
Inorganic Functional Materials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan.
Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
J Nanosci Nanotechnol. 2018 Apr 1;18(4):2702-2710. doi: 10.1166/jnn.2018.14332.
The molecular orientation of π-conjugated molecules has been reported to significantly affect the performance of organic photovoltaic devices (OPVs) based on molecular films. Hence, the control of molecular orientation is a key issue toward the improvement of OPV performance. In this research, oriented thin films of an n-type molecule, 3,4,9,10-Perylenetetracarboxylic Bisbenzimida-zole (PTCBI), were formed by deposition on in-plane oriented polythiophene (PT) films. Orientation of the PTCBI films was evaluated by polarized UV-vis spectroscopy and 2D-Grazing incidence X-ray diffraction. Results indicated that PTCBI molecules on PT film exhibit nearly edge-on and in-plane orientation (with molecular long axis along the substrate), whereas PTCBI molecules without PT film exhibit neither. OPVs composed of PTCBI molecular film with and without PT were fabricated and evaluated for correlation of orientation with performance. The OPVs composed of PTCBI film with PT showed higher power conversion efficiency (PCE) than that of film without PT. The experiment indicated that in-plane orientation of PTCBI molecules absorbs incident light more efficiently, leading to increase in PCE.
据报道，π共轭分子的分子取向会显著影响基于分子薄膜的有机光伏器件（OPV）的性能。因此，控制分子取向是提高OPV性能的关键问题。在本研究中，通过沉积在面内取向的聚噻吩（PT）薄膜上，形成了n型分子3,4,9,10-苝四羧酸双苯并咪唑（PTCBI）的取向薄膜。通过偏振紫外可见光谱和二维掠入射X射线衍射对PTCBI薄膜的取向进行了评估。结果表明，PT薄膜上的PTCBI分子呈现出近乎边缘取向和面内取向（分子长轴沿基底方向），而没有PT薄膜时，PTCBI分子则不呈现这两种取向。制备了由有PT和无PT的PTCBI分子薄膜组成的OPV，并评估了取向与性能之间的相关性。由有PT的PTCBI薄膜组成的OPV显示出比无PT薄膜更高的功率转换效率（PCE）。实验表明，PTCBI分子的面内取向能更有效地吸收入射光，从而导致PCE增加。
