Enhanced sub-bandgap efficiency of a solid-state organic intermediate band solar cell using triplet-triplet annihilation
Energy and Environmental Science
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Lin, Y., Koch, M., Brigeman, A., Freeman, D., Zhao, L., Bronstein, H., Giebink, N., et al. (2017). Enhanced sub-bandgap efficiency of a solid-state organic intermediate band solar cell using triplet-triplet annihilation. Energy and Environmental Science, 10 (6), 1465-1475. https://doi.org/10.1039/c6ee03702j
© The Royal Society of Chemistry 2017. Conventional solar cells absorb photons with energy above the bandgap of the active layer while sub-bandgap photons are unharvested. One way to overcome this loss is to capture the low energy light in the triplet state of a molecule capable of undergoing triplet-triplet annihilation (TTA), which pools the energy of two triplet states into one high energy singlet state that can then be utilized. This mechanism underlies the function of an organic intermediate band solar cell (IBSC). Here, we report a solid-state organic IBSC that shows enhanced photocurrent derived from TTA that converts sub-bandgap light into charge carriers. Femtosecond resolution transient absorption spectroscopy and delayed fluorescence spectroscopy provide evidence for the triplet sensitization and upconversion mechanisms, while external quantum efficiency measurements in the presence of a broadband background light demonstrate that sub-bandgap performance enhancements are achievable in this device. The solid-state architecture introduced in this work serves as an alternative to previously demonstrated solution-based IBSCs, and is a compelling model for future research efforts in this area.
European Commission Horizon 2020 (H2020) ERC (679789)
External DOI: https://doi.org/10.1039/c6ee03702j
This record's URL: https://www.repository.cam.ac.uk/handle/1810/302387