title: Efficient Photocurrent Enhancement from Porphyrin Molecules on Plasmonic Copper Arrays: Beneficial Utilization of Copper Nanoanntenae on Plasmonic Photoelectric Conversion Systems.
abstract: We demonstrated the usefulness of Cu light-harvesting plasmonic nanoantennae for the development of inexpensive and efficient artificial organic photoelectric conversion systems. The systems consisted of the stacked structures of layers of porphyrin as a dye molecule, oxidation-suppressing layers, and plasmonic Cu arrayed electrodes. To accurately evaluate the effect of Cu nanoantenna on the porphyrin photocurrent, the production of Cu2O by the spontaneous oxidation of the electrode surfaces, which can act as a photoexcited species under visible light irradiation, was effectively suppressed by inserting the ultrathin linking layers consisting of 16-mercaptohexadecanoic acid, titanium oxide, and poly(vinyl alcohol) between the electrode surface and porphyrin molecules. The reflection spectra in an aqueous environment of the arrayed electrodes, which were prepared by thermally depositing Cu on two-dimensional colloidal crystals of silica with diameters of 160, 260, and 330 nm, showed clear reflection dips at 596, 703, and 762 nm, respectively, which are attributed to the excitation of localized surface plasmon resonance (LSPR). While the first dip lies within the wavelengths where the imaginary part of the Cu dielectric function is moderately large, the latter two dips lie within a region of a quite small imaginary part. Consequently, the LSPR excited at the red region provided a particularly large enhancement of porphyrin photocurrent at the Q-band (ca. 59-fold), compared to that on a Cu planar electrode. These results strongly suggest that the plasmonic Cu nanoantennae contribute to the substantial improvement of photoelectric conversion efficiency at the wavelengths, where the imaginary part of the dielectric function is small.
authors.affiliation: Department of Materials and Applied Chemistry, College of Science Technology, Nihon University , Chiyoda, Tokyo 101-8308, Japan.
authors.forename: Kosuke
authors.identifier: http://orcid.org/0000-0002-3434-4632
authors.initials: K
authors.lastname: Sugawa
authors.affiliation: Department of Materials and Applied Chemistry, College of Science Technology, Nihon University , Chiyoda, Tokyo 101-8308, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yamaguchi
authors.affiliation: Department of Materials and Applied Chemistry, College of Science Technology, Nihon University , Chiyoda, Tokyo 101-8308, Japan.
authors.forename: Natsumi
authors.initials: N
authors.lastname: Tsunenari
authors.affiliation: Department of Materials and Applied Chemistry, College of Science Technology, Nihon University , Chiyoda, Tokyo 101-8308, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Uchida
authors.affiliation: Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University , Nagasaki 852-8521, Japan.
authors.forename: Hironobu
authors.initials: H
authors.lastname: Tahara
authors.affiliation: Department of Materials and Applied Chemistry, College of Science Technology, Nihon University , Chiyoda, Tokyo 101-8308, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takeda
authors.affiliation: Department of Materials and Applied Chemistry, College of Science Technology, Nihon University , Chiyoda, Tokyo 101-8308, Japan.
authors.forename: Kyo
authors.initials: K
authors.lastname: Tokuda
authors.affiliation: Department of Materials and Applied Chemistry, College of Science Technology, Nihon University , Chiyoda, Tokyo 101-8308, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Jin
authors.affiliation: Flexible Electronics Research Center (FLEC), National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kusaka
authors.affiliation: Flexible Electronics Research Center (FLEC), National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Nobuko
authors.initials: N
authors.lastname: Fukuda
authors.affiliation: Flexible Electronics Research Center (FLEC), National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Hirobumi
authors.initials: H
authors.lastname: Ushijima
authors.affiliation: Department of Materials Science, School of Engineering, The University of Shiga Prefecture , Hikone, Shiga 522-8533, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Akiyama
authors.affiliation: Department of Materials and Applied Chemistry, College of Science Technology, Nihon University , Chiyoda, Tokyo 101-8308, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Watanuki
authors.affiliation: Department of Materials and Applied Chemistry, College of Science Technology, Nihon University , Chiyoda, Tokyo 101-8308, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Nishimiya
authors.affiliation: Department of Materials and Applied Chemistry, College of Science Technology, Nihon University , Chiyoda, Tokyo 101-8308, Japan.
authors.forename: Joe
authors.initials: J
authors.lastname: Otsuki
authors.affiliation: Department of Applied Chemistry, Faculty of Engineering, Kyushu University , 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Sunao
authors.initials: S
authors.lastname: Yamada
keywords: copper nanostructures; light-harvesting nanoantenna; localized surface plasmon resonance; photocurrent; photoelectric conversion system; porphyrin