title: Controlling the Polarity of Fullerene Derivatives to Optimize Nanomorphology in Blend Films.
abstract: Developing a design strategy to establish the compatibility of acceptor materials with donor materials is important for the rational development of organic solar cells. We synthesized 2,6-dimethoxyphenyl methanofullerene derivatives to realize an enhanced open-circuit voltage, and we investigated polarities and their effects on the film morphology of the active layer. The polarities of the synthesized fullerene derivatives were affected significantly by the presence of functional groups, such as methoxy, ether, and ester groups. Macro/nanoscopic morphological investigation and spectroscopic analysis of the blend films of the poly(3-hexylthiophene)(P3HT)/fullerene derivatives showed that a balanced polarity between materials results in the formation of optimized nanomorphology without grains and robust phase separation. Measurements of the device performance of the photovoltaic cells composed of P3HT and the fullerene derivatives confirmed the same tendency as that shown in the morphological analysis. This finding enables us to obtain an improved power conversion efficiency because of the enhanced open circuit voltage derived from the fullerene derivatives.
authors: Osaka Municipal Technical Research Institute , 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553, Japan.
authors: Fukashi
authors: F
authors: Matsumoto
authors: Osaka Municipal Technical Research Institute , 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553, Japan.
authors: Toshiyuki
authors: T
authors: Iwai
authors: Osaka Municipal Technical Research Institute , 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553, Japan.
authors: Kazuyuki
authors: K
authors: Moriwaki
authors: Osaka Municipal Technical Research Institute , 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553, Japan.
authors: Yuko
authors: Y
authors: Takao
authors: Osaka Municipal Technical Research Institute , 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553, Japan.
authors: Takatoshi
authors: T
authors: Ito
authors: Osaka Municipal Technical Research Institute , 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553, Japan.
authors: Takumi
authors: T
authors: Mizuno
authors: Osaka Municipal Technical Research Institute , 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553, Japan.
authors: Toshinobu
authors: T
authors: Ohno
keywords: fullerene derivative; morphology; open circuit voltage; organic photovoltaics; surface free energy