Oligomeric Dithienopyrrole-Thienopyrroledione (DTP-TPD) Donor-Acceptor Copolymer for Organic Photovoltaics
A new donor-acceptor copolymer system based upon a dithienopyrrole (DTP) donor moiety and a thienopyrrolodione (TPD) accepting moiety has been designed and synthesized for organic photovoltaic (OPV) applications. The TPD accepting moiety has recently gained significant attention in the OPV community and is being incorporated into a number of different polymer systems. In contrast, the DTP donor moiety has received only limited attention, likely due in part to synthetic difficulties relating to the monomer. In our hands, the bis(trimethyltin)-DTP monomer was indelibly contaminated with {approx}5% of the mono-destannylated DTP, which limited the Stille polymerization with the dibromo-TPD monomer (>;99% pure) to produce material with M{sub n} {approx} 4130 g/mol (PDI = 1.10), corresponding to around eight repeat units. Despite this limitation, UV-visible absorption spectroscopy demonstrates strong absorption for this material with a band gap of {approx}1.6 eV. Cyclic voltammetry indicates a highest occupied molecular orbital (HOMO) energy level of -5.3 eV, which is much lower than calculations predicted. Initial bulk heterojunction OPV devices fabricated with the fullerene acceptor phenyl C61 butyric acid methyl ester (PCBM) exhibit V{sub oc} {approx} 700 mV, which supports the deep HOMO value obtained from CV. These results suggest the promise of this copolymer system.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy Solar Energy Technologies Program
- DOE Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1049631
- Resource Relation:
- Conference: [Proceedings] 37th IEEE Photovoltaic Specialists Conference (PVSC '11), 19-24 June 2011, Seattle, Washington; Related Information: See NREL/CP-5200-50660 for preprint
- Country of Publication:
- United States
- Language:
- English
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