Electron-deficient N-alkyloyl derivatives of thieno[3,4-c]pyrrole-4,6-dione yield efficient polymer solar cells with open-circuit voltages > 1 v

Abstract
Poly(benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymer donors yield some of the highest open-circuit voltages (V OC, ca. 0.9 V) and fill factors (FF, ca. 70%) in conventional bulk-heterojunction (BHJ) solar cells with PCBM acceptors. Recent work has shown that the incorporation of ring substituents into the side chains of the BDT motifs in PBDTTPD can induce subtle variations in material properties, resulting in an increase of the BHJ device VOC to ∼1 V. In this contribution, we report on the synthesis of N-alkyloyl-substituted TPD motifs (TPD(CO)) and show that the electron-deficient motifs can further lower both the polymer LUMO and HOMO levels, yielding device VOC > 1 V (up to ca. 1.1 V) in BHJ solar cells with PCBM. Despite the high VOC achieved (i.e., low polymer HOMO), BHJ devices cast from TPD(CO)-based polymer donors can reach power conversion efficiencies (PCEs) of up to 6.7%, making these promising systems for use in the high-band-gap cell of tandem solar cells. © 2014 American Chemical Society.

Citation
Warnan, J., Cabanetos, C., Bude, R., El Labban, A., Li, L., & Beaujuge, P. M. (2014). Electron-Deficient N-Alkyloyl Derivatives of Thieno[3,4-c]pyrrole-4,6-dione Yield Efficient Polymer Solar Cells with Open-Circuit Voltages > 1 V. Chemistry of Materials, 26(9), 2829–2835. doi:10.1021/cm5002303

Acknowledgements
The authors acknowledge financial support under Baseline Research Funding from King Abdullah University of Science and Technology (KAUST). The authors thank KAUST Analytical Core Laboratories for mass spectrometry, SEC measurements, and elemental analyses, and Sandra Seywald (MPIP - Mainz, Germany) for additional SEC measurements. The authors thank the Advanced Imaging and Characterization Laboratories at KAUST for technical support. Portions of this research were carried out at the Stanford Synchrotron Radiation Lightsource user facility, operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences.

Publisher
American Chemical Society (ACS)

Journal
Chemistry of Materials

DOI
10.1021/cm5002303

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