Hybrid dye-sensitized solar cells are typically composed of mesoporous titania (TiO2), light-harvesting dyes, and organic molecular hole-transporters. Correctly matching the electronic properties of the materials is critical to ensure efficient device operation. In this study, TiO 2 is synthesized in a welldefined morphological confinement that arises from the self-assembly of a diblock copolymer - poly(isoprene-b-ethylene oxide) (Pl-b-PEO). The crystallization environment, tuned by the inorganic (TiO2 mass) to organic (polymer) ratio, is shown to be a decisive factor in determining the distribution of sub-bandgap electronic states and the associated electronic function in solid-state dye-sensitized solar cells. Interestingly, the tuning of the sub-bandgap states does not appear to strongly influence the charge transport and recombination in the devices. However, increasing the depth and breadth of the density of sub-bandgap states correlates well with an increase in photocurrent generation, suggesting that a high density of these sub-bandgap states is critical for efficient photo-induced electron transfer and charge separation. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: P. Docampo and S. Guldin contributed equally to this work. This work was funded in part by by the EPSRC Nanotechnology Grand Challenges Energy grant (EP/F056702/1), and EP/F065884/1, the Department of Energy (DE-FG02 87ER45298) through the Cornell Fuel Cell Institute (CFCI), the National Science Foundation (DMR-0605856), and the Cornell Universiy KAUST Center for Research and Education. S.H. acknowledges a scholarship of the Bayerische Graduiertenforderung and funding from European RTN-6 Network "Polyfilm". We thank Natalie Plank for her assistance with the SEM, Mathias Kolle for the graphic design and Dominik Eder for the nitrogen sorption measurements and useful discussions, Frederic Sauvage from EPFL for information concerning the porosity and surface area of the standard Dyesol Paste and Hidetoshi Miura from Chemicrea inc. Japan for supplying the D102 sensitizer. Supporting Information is available online from Wiley InterScience or from the authors.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.