title: Alkyl-functionalized organic dyes for efficient molecular photovoltaics.
abstract: We designed and synthesized new alkyl-functionalized organic dyes, MK-1 and MK-2, for dye-sensitized solar cells (DSSCs). Based on the MK-2 dye, a high performance of efficiency (eta, 7.7%; short-circuit current density Jsc = 14.0 mA cm-2, open-circuit voltage Voc = 0.74 V, and fill factor FF = 0.74) was achieved under AM 1.5 G irradiation (100 mW cm-2). Remarkably, the relatively higher Voc for DSSCs based on MK-1 and MK-2 dyes, which have long alkyl chains, were observed among the organic dyes caused by the increasing of the electron lifetime in the conduction band of TiO2. Our molecular design of alkyl-functionalized dyes strongly suggests the promising performance of molecular photovoltaics based on organic dyes.
authors.affiliation: National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan. n-koumura@aist.go.jp
authors.forename: Nagatoshi
authors.initials: N
authors.lastname: Koumura
authors.forename: Zhong-Sheng
authors.initials: ZS
authors.lastname: Wang
authors.forename: Shogo
authors.initials: S
authors.lastname: Mori
authors.forename: Masanori
authors.initials: M
authors.lastname: Miyashita
authors.forename: Eiji
authors.initials: E
authors.lastname: Suzuki
authors.forename: Kohjiro
authors.initials: K
authors.lastname: Hara