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Low‐Energy‐Gap Organic Based Acceptor–Donor–Acceptor π‐Conjugated Small Molecules for Bulk‐Heterojunction Organic Solar Cells
Author(s) -
Castro Edison,
CabreraEspinoza Andrea,
Deemer Eva,
Echegoyen Luis
Publication year - 2015
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201500552
Subject(s) - carbazole , thiophene , chemistry , acceptor , electron acceptor , electron donor , organic solar cell , photochemistry , conjugated system , energy conversion efficiency , polymer solar cell , molecule , photovoltaic system , organic chemistry , materials science , optoelectronics , polymer , catalysis , ecology , physics , biology , condensed matter physics
We describe the detailed syntheses and characterization of two new electron‐donor molecules based on an acceptor–donor–acceptor (A–D–A) structure with carbazole as the electron‐rich building block, benzothiadiazole (BT) as the electron‐acceptor building block and octylrhodanine as the end group. We also examined the effects of a thiophene group as a spacer between the BT and the carbazole units on the optoelectronic, morphological and photovoltaic properties. The presence of the thiophenes has pronounced effects on both the optical and electrical properties. ECTBT , which contains thiophenes units, showed a red‐shifted absorption and a lower HOMO level compared to ECBT , which has no thiophene spacers. Optimized photovoltaic device fabrication based on ECTBT and [6,6]‐phenyl‐C 70 ‐butyric acid methyl ester (PC 71 BM) in a 1:1.5 ratio (w/w) exhibited the best power conversion efficiency (PCE), at 3.26 %.