Issue 12, 2012

Molecular engineering of cocktail co-sensitization for efficient panchromatic porphyrin-sensitized solar cells

Abstract

Co-sensitization of two or more dyes with complementary absorption spectra on a semiconductor film is an effective approach to enhance the performance of a dye-sensitized solar cell (DSSC). Porphyrin sensitizer YD2-oC8 showed outstanding photovoltaic performance co-sensitized with an organic dye to cover the entire visible spectral region, 400–700 nm. To promote the light-harvesting capability beyond 700 nm, a porphyrin dimer (YDD6) was synthesized for a co-sensitized system. We report a systematic approach for engineering of molecular co-sensitization of TiO2 films in a cocktail solution containing YD2-oC8, an organic dye (CD4) and YDD6 in a specific molar ratio to optimize the photovoltaic performance of the device. The resulting device showed panchromatic spectral features in the IPCE action spectrum in the region 400–700 nm attaining efficiencies of 75–80%; the spectrum is extended to the near-IR region attaining 40–45% in 700–800 nm region, giving JSC/mA cm−2 = 19.28, VOC/mV = 753, FF = 0.719, and η = 10.4% under standard AM 1.5 G one-sun irradiation. This performance is superior to what is obtained from the individual single-dye devices and the two-dye co-sensitized systems. The shifts of TiO2 potential upon dye uptake and the kinetics of charge recombination were examined through measurements of the charge extraction (CE) and intensity-modulated photovoltage spectroscopy (IMVS), respectively. Five co-sensitized systems were investigated to demonstrate that suppression of dye aggregation of YDD6 in the co-sensitized film is a key factor to further improve the device performance.

Graphical abstract: Molecular engineering of cocktail co-sensitization for efficient panchromatic porphyrin-sensitized solar cells

Supplementary files

Article information

Article type
Paper
Submitted
17 Jul 2012
Accepted
14 Aug 2012
First published
14 Aug 2012

Energy Environ. Sci., 2012,5, 9843-9848

Molecular engineering of cocktail co-sensitization for efficient panchromatic porphyrin-sensitized solar cells

H. Wu, Z. Ou, T. Pan, C. Lan, W. Huang, H. Lee, N. M. Reddy, C. Chen, W. Chao, C. Yeh and E. W. Diau, Energy Environ. Sci., 2012, 5, 9843 DOI: 10.1039/C2EE22870J

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