title: Controlled interfacial electron dynamics in highly efficient Zn2 SnO4 -based dye-sensitized solar cells.
abstract: Among ternary oxides, Zn2 SnO4 (ZSO) is considered for dye-sensitized solar cells (DSSCs) because of its wide bandgap, high optical transmittance, and high electrical conductivity. However, ZSO-based DSSCs have a poor performance record owing largely to the absence of systematic efforts to enhance their performance. Herein, general strategies are proposed to improve the performance of ZSO-based DSSCs involving interfacial engineering/modification of the photoanode. A conformal ZSO thin film (blocking layer) deposited at the fluorine-doped tin oxide-electrolyte interface by pulsed laser deposition suppressed the back-electron transfer effectively while maintaining a high optical transmittance, which resulted in a 22 % improvement in the short-circuit photocurrent density. Surface modification of ZSO nanoparticles (NPs) resulted in an ultrathin ZnO shell layer, a 9 % improvement in the open-circuit voltage, and a 4 % improvement in the fill factor because of the reduced electron recombination at the ZSO NPs-electrolyte interface. The ZSO-based DSSCs exhibited a faster charge injection and electron transport than their TiO2 -based counterparts, and their superior properties were not inhibited by the ZnO shell layer, which indicates their feasibility for highly efficient DSSCs. Each interfacial engineering strategy could be applied to the ZSO-based DSSC independently to lead to an improved conversion efficiency of 6 %, a very high conversion efficiency for a non-TiO2 based DSSC.
authors.affiliation: WCU Hybrid Materials Program, Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea).
authors.forename: Seong Sik
authors.initials: SS
authors.lastname: Shin
authors.forename: Dong Wook
authors.initials: DW
authors.lastname: Kim
authors.forename: Daesub
authors.initials: D
authors.lastname: Hwang
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Suk
authors.forename: Lee Seul
authors.initials: LS
authors.lastname: Oh
authors.forename: Byung Suh
authors.initials: BS
authors.lastname: Han
authors.forename: Dong Hoe
authors.initials: DH
authors.lastname: Kim
authors.forename: Ju Seong
authors.initials: JS
authors.lastname: Kim
authors.forename: Dongho
authors.initials: D
authors.lastname: Kim
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Kug Sun
authors.initials: KS
authors.lastname: Hong
mesh_terms: D011211:Electric Power Supplies; D004563:Electrochemistry; D004583:Electrons; D013472:Sunlight; D017971:Tin Compounds / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D017971:Tin Compounds; C045358:stannic oxide; D015034:Zinc Oxide
keywords: electrochemistry; electron transfer; energy conversion; surface chemistry; zinc stannate