Chuang, S.-Y.S.-Y.ChuangChen, H.-L.H.-L.ChenLee, W.-H.W.-H.LeeHuang, Y.-C.Y.-C.HuangSu, W.-F.W.-F.SuJen, W.-M.W.-M.JenWEI-FANG SUCHUN-WEI CHENHSUEN-LI CHEN2020-05-122020-05-122009https://scholars.lib.ntu.edu.tw/handle/123456789/491333In this paper, we demonstrate the strong influence of the regioregularity (RR) of poly(3-hexylthiophene) (P3HT) on the optical anisotropy of hybrid P3HT/fullerene films before and after thermal annealing. We determined the conversion efficiency and characterized the optical anisotropy of P3HT/6,6-phenyl-C61-butyric acid methyl ester (PCBM) blends featuring various values of RR. Unlike grazing-incidence X-ray diffraction analysis, optical anisotropic measurement provides a clear and convenient view of the polymer orientation and the device anisotropic absorption at the same time. By calculating the in-plane and out-of-plane optical constants (extinction coefficients and refractive indices), we determined that the optical anisotropy of P3HT/PCBM films was improved in both orientations upon increasing the RR. Upon increasing the thermal annealing temperature, the main chains of high-RR P3HT were converted from an amorphous structure to an alignment parallel to the substrate, resulting in higher optical anisotropy. The degree of anisotropy of the high-RR P3HT/PCBM blend was up to six times higher than that of the low-RR sample. This strong RR effect on optical anisotropy was also evident in the power conversion efficiency of large-area P3HT/PCBM-based organic solar cells. © 2009 The Royal Society of Chemistry.[SDGs]SDG7Amorphous structures; Anisotropic absorption; Before and after; Butyric acids; Chain orientation; Degree of anisotropy; Extinction coefficients; Grazing incidence X-ray diffraction; High efficiency; In-plane; Main chains; Methyl esters; Optical anisotropic; Organic solar cell; Out-of-plane; Poly-3-hexylthiophene; Power conversion efficiencies; Regioregularity; RR-P3HT; Thermal-annealing; Composite films; Conversion efficiency; Esters; Fatty acids; Light transmission; Optical anisotropy; Optical constants; Photovoltaic cells; Refractive index; Solar cells; Solar energy; X ray diffraction analysis; Optical filmsjournal article10.1039/b904870g2-s2.0-68149163701https://www.scopus.com/inward/record.uri?eid=2-s2.0-68149163701&doi=10.1039%2fb904870g&partnerID=40&md5=237998d17ba211ecc3348b2e7da69800