title: Metal-free organic dyes for TiO2 and ZnO dye-sensitized solar cells.
abstract: We report the synthesis and characterization of new metal-free organic dyes (namely B18, BTD-R, and CPTD-R) which designed with D-π-A concept to extending the light absorption region by strong conjugation group of π-linker part and applied as light harvester in dye sensitized solar cells (DSSCs). We compared the photovoltaic performance of these dyes in two different photoanodes: a standard TiO2 mesoporous photoanode and a ZnO photoanode composed of hierarchically assembled nanostructures. The results demonstrated that B18 dye has better photovoltaic properties compared to other two dyes (BTD-R and CPTD-R) and each dye has higher current density (Jsc) when applied to hierarchical ZnO nanocrystallites than the standard TiO2 mesoporous film. Transient photocurrent and photovoltage decay measurements (TCD/TVD) were applied to systematically study the charge transport and recombination kinetics in these devices, showing the electron life time (τR) of B18 dye in ZnO and TiO2 based DSSCs is higher than CPTD-R and BTD-R based DSSCs, which is consistent with the photovoltaic performances. The conversion efficiency in ZnO based DSSCs can be further boosted by 35%, when a compact ZnO blocking layer (BL) is applied to inhibit electron back reaction.
authors.affiliation: SENSOR Lab, Department of Information Engineering, University of Brescia, Via Valotti 9, 25133 Brescia, Italy.|CNR-INO SENSOR Lab, Via Branze 45, 25123 Brescia, Italy.
authors.forename: Gurpreet Singh
authors.initials: GS
authors.lastname: Selopal
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
authors.forename: Hui-Ping
authors.initials: HP
authors.lastname: Wu
authors.affiliation: Michael Grätzel Center for Mesoscopic Solar Cells, Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074 (P. R. China).
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.
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Chang
authors.affiliation: Michael Grätzel Center for Mesoscopic Solar Cells, Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074 (P. R. China).
authors.forename: Mingkui
authors.initials: M
authors.lastname: Wang
authors.affiliation: CNR-INO SENSOR Lab, Via Branze 45, 25123 Brescia, Italy.|Luleå University of Technology, 971 98 Luleå, Sweden.
authors.forename: Alberto
authors.initials: A
authors.lastname: Vomiero
authors.affiliation: SENSOR Lab, Department of Information Engineering, University of Brescia, Via Valotti 9, 25133 Brescia, Italy.|CNR-INO SENSOR Lab, Via Branze 45, 25123 Brescia, Italy.
authors.forename: Isabella
authors.initials: I
authors.lastname: Concina
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
authors.forename: Eric Wei-Guang
authors.initials: EW
authors.lastname: Diau