title: Molecular engineering of organic dyes with a hole-extending donor tail for efficient all-solid-state dye-sensitized solar cells.
abstract: We report a new concept for the design of metal-free organic dyes (OD5-OD9) with an extended donor-π-acceptor (D-π-A) molecular framework, in which the donor terminal unit is attached by a hole-extending side chain to retard back electron transfer and charge recombination; the π-bridge component contains varied thiophene-based substituents to enhance the light-harvesting ability of the device. The best dye (OD9) has a D-A-π-A configuration with the hexyloxyphenylthiophene (HPT) side chain as a hole-extension component and a benzothiadiazole (BTD) internal acceptor as a π-extension component. The co-sensitization of OD9 with the new porphyrin dye LW24 enhanced the light-harvesting ability to 800 nm; thus, a power conversion efficiency 5.5 % was achieved. Photoinduced absorption (PIA) and transient absorption spectral (TAS) techniques were applied to account for the observed trend of the open-circuit voltage (VOC ) of the devices. This work provides insights into the molecular design, photovoltaic performance, and kinetics of charge recombination.
authors.affiliation: Michael Grätzel Center for Mesoscopic Solar Cells, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074 (PR China), Fax: (+86) 27-87792225.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010 (Taiwan), Fax: (+886) 3-5723764.
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Chang
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010 (Taiwan), Fax: (+886) 3-5723764.
authors.forename: Hsu-Yang
authors.initials: HY
authors.lastname: Cheng
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010 (Taiwan), Fax: (+886) 3-5723764.
authors.forename: Hui-Ping
authors.initials: HP
authors.lastname: Wu
authors.affiliation: Michael Grätzel Center for Mesoscopic Solar Cells, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074 (PR China), Fax: (+86) 27-87792225.|Department of Materials Engineering, Monash University, Melbourne, Victoria, 3800 (Australia).
authors.forename: Yibing
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Michael Grätzel Center for Mesoscopic Solar Cells, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074 (PR China), Fax: (+86) 27-87792225. mingkui.wang@mail.hust.edu.cn.
authors.forename: Mingkui
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010 (Taiwan), Fax: (+886) 3-5723764. diau@mail.nctu.edu.tw.
authors.forename: Eric Wei-Guang
authors.initials: EW
authors.lastname: Diau
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D011211:Electric Power Supplies; D011166:Porphyrins / Q000737:chemistry; D012993:Solar Energy; D013830:Thiadiazoles / Q000737:chemistry; D013876:Thiophenes / Q000737:chemistry
chemical_list: D000814:Aniline Compounds; D004396:Coloring Agents; D011166:Porphyrins; D013830:Thiadiazoles; D013876:Thiophenes; C015700:benzo-1,2,3-thiadiazole
keywords: donor-acceptor systems; dyes; porphyrinoids; sensitizers; solar cells