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Molecular Engineering of Simple Phenothiazine‐Based Dyes To Modulate Dye Aggregation, Charge Recombination, and Dye Regeneration in Highly Efficient Dye‐Sensitized Solar Cells
Author(s) -
Hua Yong,
Chang Shuai,
He Jian,
Zhang Caishun,
Zhao Jianzhang,
Chen Tao,
Wong WaiYeung,
Wong WaiKwok,
Zhu Xunjin
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201304897
Subject(s) - dye sensitized solar cell , photocurrent , phenothiazine , chemistry , energy conversion efficiency , photochemistry , electrolyte , solar cell , dimer , absorption (acoustics) , materials science , optoelectronics , organic chemistry , electrode , medicine , pharmacology , composite material
Abstract A series of simple phenothiazine‐based dyes, namely, TP , EP , TTP , ETP , and EEP have been developed, in which the thiophene (T), ethylenedioxythiophene (E), their dimers, and mixtures are present to modulate dye aggregation, charge recombination, and dye regeneration for highly efficient dye‐sensitized solar cell (DSSC) applications. Devices sensitized by the dyes TP and TTP display high power conversion efficiencies (PCEs) of 8.07 ( J sc =15.2 mA cm −2 , V oc =0.783 V, fill factor (FF)=0.679) and 7.87 % ( J sc =16.1 mA cm −2 , V oc =0.717 V, FF=0.681), respectively; these were measured under simulated AM 1.5 sunlight in conjunction with the I − /I 3 − redox couple. By replacing the T group with the E unit, EP ‐based DSSCs had a slightly lower PCE of 7.98 % with a higher short‐circuit photocurrent ( J sc ) of 16.7 mA cm −2 . The dye ETP , with a mixture of E and T, had an even lower PCE of 5.62 %. Specifically, the cell based on the dye EEP , with a dimer of E, had inferior J sc and V oc values and corresponded to the lowest PCE of 2.24 %. The results indicate that the photovoltaic performance can be finely modulated through structural engineering of the dyes. The selection of T analogues as donors can not only modulate light absorption and energy levels, but also have an impact on dye aggregation and interfacial charge recombination of electrons at the interface of titania, electrolytes, and/or oxidized dye molecules; this was demonstrated through DFT calculations, electrochemical impedance analysis, and transient photovoltage studies.