The Influence of an Inorganic Interlayer on Exciton Separation in Hybrid Solar Cells
Armstrong, Claire L
Davis, Nathaniel JKL
MacManus-Driscoll, Judith L
Böhm, Marcus L
Musselman, Kevin P
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Armstrong, C. L., Price, M., Muñoz-Rojas, D., Davis, N. J., Abdi-Jalebi, M., Friend, R., Greenham, N., et al. (2015). The Influence of an Inorganic Interlayer on Exciton Separation in Hybrid Solar Cells. ACS Nano, 9 11863-11871. https://doi.org/10.1021/acsnano.5b05934
It has been shown that in hybrid polymer-inorganic photovoltaic devices, not all the photogenerated excitons dissociate at the interface immediately, but can instead exist temporarily as bound charge pairs (BCPs). Many of these BCPs do not contribute to the photocurrent as their long lifetime as a bound species promotes various charge carrier recombination channels. Fast and efficient dissociation of BCPs is therefore considered a key challenge in improving the performance of polymer-inorganic cells. Here we investigate the influence of an inorganic energy cascading Nb2O5 interlayer on the charge carrier recombination channels in poly(3- hexylthiophene-2,5-diyl) (P3HT)-TiO2 and PbSe colloidal quantum dot-TiO2 photovoltaic devices. We demonstrate that the additional Nb2O5 film leads to a suppression of BCPformation at the heterojunction of the P3HT cells and also a reduction in the non-geminate recombination mechanisms in both types of cells. Furthermore we provide evidence that the reduction in non-geminate recombination in the P3HT-TiO2 devices is due in part to the passivation of deep mid-gap trap states in the TiO2, which prevents trap assisted Shockley-ReadHall recombination. Consequently a significant increase in both the open-circuit voltage and the short-circuit current was achieved, in particular for P3HT-based solar cells where the power conversion efficiency increased by 39%.
C.L.A. acknowledges the Sims Scholarship from the University of Cambridge. J.L.M.D. acknowledges funding from the European Research Council Advanced Investigator Grant NOVOX ERC-2009-adG247276ERC. M.L.B. thanks the German National Academic Foundation (Studienstiftung) and the Engineering and Physical Sciences Research Council Grant RG53717 KJZA/098 for funding.
European Research Council (247276)
External DOI: https://doi.org/10.1021/acsnano.5b05934
This record's URL: https://www.repository.cam.ac.uk/handle/1810/252494
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Licence URL: http://creativecommons.org/licenses/by/4.0/