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Comparative Studies on Optical, Redox, and Photovoltaic Properties of a Series of D–A–D and Analogous D–A Chromophores
Author(s) -
ZitzlerKunkel André,
Lenze Martin R.,
Schnier Tobias,
Meerholz Klaus,
Würthner Frank
Publication year - 2014
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201400455
Subject(s) - chromophore , materials science , acceptor , fluorescence , photochemistry , electron acceptor , optics , chemistry , physics , condensed matter physics
A series of new symmetrical donor‐acceptor‐donor (D−A−D) dyes based on s ‐indacene‐1,3,5,7(2 H ,6 H )‐tetraone as an acceptor unit containing varying electron donating moieties and analogous donor‐acceptor (D−A) chromophores with indane‐1,3‐dione as an acceptor are synthesized. By employing these two sets of dyes, the influence of a scaffold change from unsymmetric push‐pull (D−A) to symmetrical (D−A−D) systems on optical, electrochemical, and photovoltaic properties are explored. Detailed comparative studies reveal favorable optical characteristics and considerably decreased bandgaps for the D−A−D dyes compared to those of the reference D−A chromophores. Accordingly, the evaluation of the present dyes as donor materials in bulk heterojunction (BHJ) solar cells in combination with fullerene derivatives PC 61 BM or PC 71 BM as acceptors afforded significantly improved performance for devices based on D−A−D blends (up to a factor of 4 compared to the respective D‐A reference) with power conversion efficiencies of up to 2.8%. In less polar solvents such as toluene, some of the novel D−A−D chromophores exhibit unexpectedly high fluorescence quantum yields Φ em of up to unity, in striking contrast to their weakly fluorescent D‐A counterparts.