title: Substitution of a hydroxamic acid anchor into the MK-2 dye for enhanced photovoltaic performance and water stability in a DSSC.
abstract: An efficient synthetic protocol to functionalize the cyanoacrylic acid anchoring group of commercially available MK-2 dye with a highly water-stable hydroxamate anchoring group is described. Extensive characterization of this hydroxamate-modified dye (MK-2HA) reveals that the modification does not affect its favorable optoelectronic properties. Dye-sensitized solar cells (DSSCs) prepared with the MK-2HA dye attain improved efficiency (6.9%), relative to analogously prepared devices with commercial MK-2 and N719 dyes. The hydroxamate anchoring group also contributes to significantly increased water stability, with a decrease in the rate constant for dye desorption of MK-2HA relative to MK-2 in the presence of water by as much as 37.5%. In addition, the hydroxamate-anchored dye undergoes essentially no loss in DSSC efficiency and the external quantum efficiency improves when up to 20% water is purposefully added to the electrolyte. In contrast, devices prepared with the commercial dye suffer a 50% decline in efficiency under identical conditions, with a concomitant decrease in external quantum efficiency. Collectively, our results indicate that covalent functionalization of organic dyes with hydroxamate anchoring groups is a simple and efficient approach to improving the water stability of the dye-semiconductor interface and overall device durability.
authors.affiliation: Yale Energy Sciences Institute and Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, USA. victor.batista@yale.edu gary.brudvig@yale.edu robert.crabtree@yale.edu charles.schmuttenmaer@yale.edu.
authors.forename: C
authors.initials: C
authors.lastname: Koenigsmann
authors.forename: T S
authors.initials: TS
authors.lastname: Ripolles
authors.forename: B J
authors.initials: BJ
authors.lastname: Brennan
authors.forename: C F A
authors.initials: CF
authors.lastname: Negre
authors.forename: M
authors.initials: M
authors.lastname: Koepf
authors.forename: A C
authors.initials: AC
authors.lastname: Durrell
authors.forename: R L
authors.initials: RL
authors.lastname: Milot
authors.forename: J A
authors.initials: JA
authors.lastname: Torre
authors.forename: R H
authors.initials: RH
authors.lastname: Crabtree
authors.forename: V S
authors.initials: VS
authors.lastname: Batista
authors.forename: G W
authors.initials: GW
authors.lastname: Brudvig
authors.forename: J
authors.initials: J
authors.lastname: Bisquert
authors.forename: C A
authors.initials: CA
authors.lastname: Schmuttenmaer