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

Hui Ping Wu, Zih Wei Ou, Tsung Yu Pan, Chi Ming Lan, Wei Kai Huang, Hsuan Wei Lee, N. Masi Reddy, Chien Tien Chen*, Wei Shan Chao, Chen Yu Yeh, Wei-Guang Diau

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

130 Scopus citations

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.

Original languageEnglish
Pages (from-to)9843-9848
Number of pages6
JournalEnergy and Environmental Science
Volume5
Issue number12
DOIs
StatePublished - 1 Dec 2012

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