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Optimizing the photocurrent efficiency of dye-sensitized solar cells through the controlled aggregation of chalcogenoxanthylium dyes on nanocrystalline titania films

Mann, Jonathan R. and Gannon, Michael K. and Fitzgibbons, Thomas C. and Detty, Michael R. and Watson, David F. (2008) Optimizing the photocurrent efficiency of dye-sensitized solar cells through the controlled aggregation of chalcogenoxanthylium dyes on nanocrystalline titania films. JOURNAL OF PHYSICAL CHEMISTRY C, 112 (34). pp. 13057-13061.

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jp803990b

Abstract

Chalcogenoxanthylium dyes were characterized as sensitizers of nanocrystalline titania in dye-sensitized solar cells (DSSCs). Four series of dyes were characterized: 2,7-bis(dimethylamino)-9-(2-thienyl-5-carboxy)chalcogenoxanthylium dyes (I-E, where E = 0, S, Se); 2,7-bis(dimethylamino)-9-(3-thienyl-2-carboxy)chalcogenoxanthylium dyes (2-E, where E = S, Se); a 2,7-bis(dimethylamino)-9-(2-thienyl)selenoxanthylium dye (3-Se); 4-Se, a constrained analog of 1-Se. The orientation and aggregation state of the dyes were controlled by varying the position of the surface-attachment group relative to the xanthylium core. Series 1 dyes and 4-Se underwent H-aggregation on titania surfaces, whereas series 2 dyes adsorbed in amorphous monolayers. (3-Se did not adsorb appreciably to titania films, due to the lack of a tethering group.) The H-aggregated dyes exhibited broader absorption bands, increased light-harvesting efficiencies, and improved photoelectrochemical performance compared to the dyes which adsorbed in amorphous monolayers. The maximum incident photon-to-current efficiencies (IPCEs) of series I dyes ranged from 70% to 84%, whereas those of 2-S and 2-Se were 11% and 20%. Our findings reveal that the light-harvesting efficiency, IPCE, and absorbed photon-to-current efficiency (APCE) of DSSCs with organic dyes can be optimized by systematically varying the structure of the dyes and their orientation and aggregation state on the surface.

Item Type:Article
Subjects:Technology > Nanotechnology and energy applications
ID Code:1429
Deposited By:Farnush Anwar
Deposited On:12 Dec 2008 16:34
Last Modified:13 Jan 2009 14:58

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