Spectrally dependent photocurrent generation in aggregated MEH-PPV:PPDI donor–acceptor blends
- 作者：Yinhua Zhou ; Yanan Wang ; Weicai Wu ; Huan Wang ; Liang Han ; Wenjing Tian ; Heinz Bä ; ssler
- 关键词：Annealing ; Aggregate ; Absorption ; Morphology ; Photovoltaic ; Exciton dissociation
- 刊名：Solar Energy Materials and Solar Cells
- 出版年：2007
- 期刊代码：81_09270248
- 类别：ce
- 出版时间：23 November 2007
- 卷：91
- 期：19
- 页码：1842-1848
- 文件大小：627 K
摘要
Films of MEH-PPV and PPDI blends with weight ratio 1:2 have been prepared by spin-coating and annealing between 0 and 60 min at 95 °C. The films were characterized by absorption spectroscopy and atomic force microscopy (AFM). The main emphasis has been on the photon conversion efficiency in the photovoltaic cells as a function of excitation wavelength and applied voltage/electric field. Site selective excitation at wavelengths at which either non-aggregated bulk PPDI or dimers/aggregates of PPDI absorb prove that (i) the rate-limiting process for power conversion is the field-assisted escape of optically generated geminate electron–hole pairs from their mutual coulombic potential and (ii) the photogeneration yield depends on the donor–acceptor topology. A significant difference of the yield has been noted when alkoxy-pendent groups in MEH-PPV are replaced by phenyl-alkoxy groups.