Ultrafast Charge‐Transfer Reactions of Indoline Dyes with Anchoring Alkyl Chains of Varying Length in Mesoporous ZnO Solar Cells. Issue 5 (4th February 2015)

• Record Type: Journal Article
• Authors: Rohwer, Egmont; Minda, Iulia; Tauscher, Gabriele; Richter, Christoph; Miura, Hidetoshi; Schlettwein, Derck; Schwoerer, Heinrich
• Is Part Of: Chemphyschem. Volume 16:Issue 5(2015)
• Page Start: 943
• Page End: 948
• Publication Date: 2015-02-04
• Subjects: dye‐sensitized solar cells -- indoline dyes -- injection rate -- pump–probe spectroscopy -- zinc oxide; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.201402784
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: Dye‐sensitized solar cells based on a mesoporous ZnO substrate were sensitized with the indoline derivatives DN91, DN216 and DN285. The chromophore is the same for each of these dyes. They differ from each other in the length of an alkyl chain, which provides a second anchor to the ZnO surface and prolongs cell lifetime. Ultrafast transient absorption measurements reveal a correlation between the length of the alkyl chain and the fastest electron‐injection process. The depopulation of the excited state and the associated emergence of the oxidized molecules are dominant spectral features in the transient absorption of the dyes with shorter alkyl chains. A slower picosecond‐scale decay proceeds at constant rate for all three derivatives and is assigned to electron transfer into the trap states of ZnO. All assignments are in good agreement with a higher quantum efficiency of charge injection leading to higher short‐circuit currents J sc for dyes with shorter alkyl chains. Abstract : Pump–probe spectroscopy studies in the ps to sub‐ps regime are performed to reveal the role of different anchor groups at indoline‐type sensitizer molecules in the charge‐carrier dynamics of ZnO‐based dye‐sensitized solar cells.