Abstract
Three extended 2,5-dithienylthiazolo[5,4-d]thiazole-based small molecule chromophores are prepared via a sustainable direct arylation approach and their physicochemical and opto-electrical material characteristics are analyzed toward integration in solution-processed bulk heterojunction organic photovoltaics. Efficient charge separation and high values of the charge transfer state energy are derived from sensitive ground and excited state absorption and photoluminescence measurements on blends of the thiazolo[5,4-d]thiazole-based electron donor components with the PC71BM fullerene acceptor. Upon implementation in organic solar cells, a maximum power conversion efficiency of 2.7% and particularly high open-circuit voltages (0.93−0.98 V) are observed, which are correlated to the charge transfer state energies as derived from photoluminescence, Fourier transform photocurrent spectroscopy and combined electrochemical and photophysical data. Furthermore, several loss processes at the origin of the modest short-circuit current densities and fill factors are elucidated.
Original language | English |
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Pages (from-to) | 1253-1261 |
Number of pages | 9 |
Journal | ChemistrySelect |
Volume | 2 |
Issue number | 3 |
DOIs | |
Publication status | Published - 1 Jan 2017 |
Funding
This work was supported by the IAP 7/05 project FS2 (Functional Supramolecular Systems), granted by the Science Policy Office of the Belgian Federal Government (BELSPO). We are also grateful for financial support by the Research Program of the Research Foundation – Flanders (FWO) (projects G.0415.14N, G.0B67.15N and M.ERA-NET project RADESOL). T. Vangerven and G. Heintges acknowledge the Agency for Innovation by Science and Technology in Flanders (IWT), and M. Van Lande-ghem the FWO, for their respective PhD grants. Hasselt University, IMO-IMOMEC and TU Eindhoven are partners within the Solliance network, the strategic alliance for research and development in the field of thin-film PV energy in the Eindhoven-Leuven-Aachen region.
Keywords
- charge transfer
- direct arylation
- donor-acceptor systems
- organic photovoltaics
- organic semiconductors