We present a novel route to hierarchical core-shell structures consisting of an anodic ZnO nanowire core surrounded by a shell of TiO2 nanosheets (ZNW@TNS). This material combines the beneficial properties of enhanced electron transport, provided by the nanowire core, with the high surface area and chemical stability of the TiO2 shell. Quasi-solid-state dye-sensitized solar cells (qssDSSCs) are prepared using different quantities of either the bare ZnO nanowires or the hierarchical nanowire structures and the effect on cell performance is examined. It is found that whilst the addition of the bare ZnO nanowires results in a decrease in cell performance, significant improvements can be achieved with the addition of small quantities of the hierarchical structures. Power conversion efficiencies of up to 7.5% are achieved under 1 Sun, AM 1.5 simulated sunlight, with a ∼30% increase compared to non-hierarchical mesoporous TiO2 films. A solid-state DSSC (ssDSSC) with a single component solid polymer also exhibits excellent efficiency of 7.2%. The improvement in cell performance is related to the improved light scattering, surface area and electron transport properties via the use of reflectance spectroscopy, BET surface area measurements and electrochemical impedance spectroscopy.
Bibliographical noteFunding Information:
D. Miles would like to acknowledge the EPSRC for funding via the Centre for Sustainable Chemical Technologies (Grant no. EP/G03768X/1 ). D. Mattia would like to thank the Royal Academy of Engineering for funding. All data created during this research are openly available from the University of Bath data archive at http://doi.org/10.15125/BATH-00155 . J. H. Kim would like to acknowledge the National Research Foundation (NRF) grant through the Korea Center for Artificial Photosynthesis (KCAP) ( 2009-0093883 ) and the Center for Advanced Meta-Materials (CAMM) ( NRF-2014M3A6B3063716 ).
© 2016 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Energy Engineering and Power Technology
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering