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Solution‐Processed Bulk‐Heterojunction Solar Cells Based on Monodisperse Dendritic Oligothiophenes
Author(s) -
Ma ChangQi,
Fonrodona Marta,
Schikora Martin C.,
Wienk Martijn M.,
Janssen René A. J.,
Bäuerle Peter
Publication year - 2008
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.200800584
Subject(s) - materials science , dispersity , homo/lumo , solar cell , band gap , energy conversion efficiency , thiophene , heterojunction , acceptor , open circuit voltage , organic solar cell , electron acceptor , hybrid solar cell , optoelectronics , quantum dot , chemical engineering , polymer solar cell , photochemistry , polymer chemistry , organic chemistry , polymer , molecule , voltage , chemistry , physics , quantum mechanics , engineering , composite material , condensed matter physics
A novel family of soluble conjugated dendritic oligothiophenes (DOTs) as monodisperse 3D macromolecular architectures was characterized with respect to optical and redox properties in solution and in solid films. Band gaps of 2.5–2.2 eV, typical for organic semiconductors, were determined as well as HOMO/LUMO energy levels ideal for efficient electron transfer to acceptors such as [6,6]‐phenyl‐C 61 ‐butyric acid methyl ester (PCBM) identifying them as suitable materials for solar cell applications. Solution‐processed bulk‐heterojunction solar cells using DOTs as electron donor and PCBM as acceptor were prepared and investigated. High open‐circuit voltages V OC of 1.0 V and power‐conversion efficiencies up to 1.72% were obtained for the DOT‐based devices. The higher generations DOTs provide the highest efficiencies. Based on the monodispersity of the DOTs, an analysis of the molar ratio between donor and acceptor in the blended film was possible leading to an optimal value of five to six thiophene units per PCBM.