Solution-Processed Organic Solar Cells with Power Conversion Efficiencies of 2.5% using Benzothiadiazole/Imide-Based Acceptors
2011; American Chemical Society; Volume: 23; Issue: 24 Linguagem: Inglês
10.1021/cm203111k
ISSN1520-5002
AutoresJason T. Bloking, Xu Han, Andrew T. Higgs, John P. Kastrop, Laxman Pandey, Joseph E. Norton, Chad Risko, Cynthia E. Chen, Jean‐Luc Brédas, Michael D. McGehee, Alan Sellinger,
Tópico(s)Organic Light-Emitting Diodes Research
ResumoA new series of electron-deficient molecules based on a central benzothiadiazole moiety flanked with vinylimides has been synthesized via Heck chemistry and used in solution-processed organic photovoltaics (OPV). Two new compounds, 4,7-bis(4-(N-hexyl-phthalimide)vinyl)benzo[c]1,2,5-thiadiazole (PI-BT) and 4,7-bis(4-(N-hexyl-naphthalimide)vinyl)benzo[c]1,2,5-thiadiazole (NI-BT), show significantly different behaviors in bulk heterojunction (BHJ) solar cells using poly(3-hexylthiophene) (P3HT) as the electron donor. Two-dimensional grazing incidence X-ray scattering (2D GIXS) experiments demonstrate that PI-BT shows significant crystallization in spin-coated thin films, whereas NI-BT does not. Density functional theory (DFT) calculations predict that while PI-BT maintains a planar structure in the ground state, steric interactions cause a twist in the NI-BT molecule, likely preventing significant crystallization. In BHJ solar cells with P3HT as donor, PI-BT devices achieved a large open-circuit voltage of 0.96 V and a maximum device power-conversion efficiency of 2.54%, whereas NI-BT containing devices only achieved 0.1% power-conversion efficiency.
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