Photovoltaic performance of dye-sensitized solar cells based on cross-linkable sensitizers and binary ionic liquid electrolyte system
Date Issued
2011
Date
2011
Author(s)
Wen, Ke-Gang
Abstract
In this thesis，we focus on the photovoltaic performance of dye-sensitized solar cells (DSSCs) based on ionic liquid electrolyte systems and cross-linkable sensitizer Ru(4,4’-dicarboxylic acid) (4,4''-bis((4-vinylbenzyloxy)methyl)-2,2''-bipyridine) (NCS)2, denoted as RuS. There are two parts in this thesis. In the first part, the photovoltaic performance depending on 3-propyl-1-methylimidazolium iodide (PMImI) and binary PMImI/1-ethyl-3-methylimidazolium dicyanamide (EMIDCA) ionic liquid electrolyte systems for DSSCs with non-crosslinked and crosslinked RuS was investigated. In the second part, RuS on TiO2 mesoporous layer was crosslinked with three different molecular weights (Mw = 428、604、912) of trimethylolpropane ethoxylate triacrylate (TET), denoted as RuSco-TET428、RuSco-TET604 and RuSco-TET912, respectively for fabricating DSSCs. The influence of molecular weight for TET on power conversion efficiency was evaluated.
In the first part, the power efficiency of DSSCs using RuS crosslinking with different concentrations of triethyleneglyco- dimethacrylate (TGDMA) and PMImI ionic liquid electrolyte systems reached 4.84 ％. By using binary ionic liquid electrolyte systems comprised of PMImI and low viscosity EMIDCA (1:1 (v/v)), the short-circuit photocurrent (Jsc) and open-circuit photovoltage (Voc) of the device were higher than those using PMImI ionic liquid electrolyte systems. As we optimized the contents of I2 and LiClO4 in binary ionic liquid electrolyte, the device exhibited higher efficiency of 6.5 % resulted from the increase of Jsc. The photovoltaic properties were also investigated by electrochemical impedance spectroscopy (EIS).
In the second part, the DSSCs based on RuS-co-TET428、RuS-co-TET604 and RuS-co-TET912 and a binary ionic liquid electrolyte gave an impressive efficiency, especially when the concentrations of TET in acetonitrile were enough (10-3 ~10-4 M) to form a single layer network with RuS. Take RuS-co-TET912 as a example, the device exhibited an excellent power conversion efficiency of 7.2 %. According to voltage decay-charge extraction measurement, the increase of cell performance was attributed to the higher electron/dye ratio and longer electron lifetime. Finally, the DSSCs based on RuS-co-TET912 in binary ionic liquid electrolyte exhibited good stability with the power efficiency remaining unchanged after 960hr at room temperature.
Subjects
crosslinkable sensitizer
DSSC
ionic liquid electrolyte
photovoltaic
electrochemical impedance
SDGs
Type
thesis
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