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Regioisomeric Effects on the Electronic Features of Indenothiophene‐Bridged D–π‐A′–A DSSC Sensitizers
Author(s) -
Chou ShuHua,
Tsai ChihHung,
Wu ChungChih,
Kumar Dhirendra,
Wong KenTsung
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.201403584
Subject(s) - dye sensitized solar cell , intramolecular force , acceptor , bathochromic shift , molar absorptivity , thiophene , energy conversion efficiency , photochemistry , molecular engineering , materials science , dipole , chemistry , optoelectronics , stereochemistry , nanotechnology , optics , organic chemistry , physics , electrode , condensed matter physics , electrolyte , fluorescence
Two D–π‐A′–A regioisomers (A‐IDT‐D and D‐IDT‐A) featuring 4,4′‐di‐ p ‐tolyl‐4 H ‐indeno[1,2‐ b ]‐thiophene as a π linker (π) between the diarylamino donor (D) and the pyrimidine–cyanoacrylic acid acceptor (A′–A) have been successfully synthesized and characterized as efficient sensitizers for the dye‐sensitized solar cells (DSSCs). The different arrangements of the D and A′–A blocks on the unsymmetrical indenothiophene (IDT) core render the dipole of IDT being along (A‐IDT‐D) or opposite (D‐IDT‐A) to the direction of intramolecular (donor‐to‐acceptor) charge transfer, and thus induce variations in the physical properties. The experimental observations correlated well with the theoretical analyses, clearly revealing the trade‐off between the molar extinction coefficient ( ε ) and the S 0 →S 1 transition energy. As a result, a superior ε value was observed for D‐IDT‐A, whereas a bathochromic shift in the absorption occurred in A‐IDT‐D. The larger ε value of D‐IDT‐A together with its more favorable energy level relative to TiO 2 led to a higher power conversion efficiency of 7.41 % for the D‐IDT‐A‐based DSSC, retaining approximately 95 % of the N719‐based DSSC efficiency. This work manifests the clear structure–property relationship for the case of donor and acceptor components being connected by an unsymmetrical π linker and provides insights for molecular engineering of organic sensitizers.