In the present work we grow anodic TiO2 nanotube layer with tube diameter ~ 500 nm and an open tube mouth. We use this morphology in dye-sensitized solar cells (DSSCs) and show that these tubes allow the construction of hybrid hierarchical photoanode structures of nanotubes with a defined and wall-conformance TiO2 nanoparticles decoration. At the same time, the large diameter allows the successful establishment of an additional (insulating) blocking layer of SiO2 or Al2O3. We show that this combination of hierarchical structure and blocking layer significantly enhances the solar cell efficiency by suppressing recombination reactions. In such a DSSC structure, the solar cell efficiency under back side illumination with AM1.5 illumination is enhanced from 5% neat tube to 7 %.
@article{arxiv.2005.01605,
title = {Large diameter TiO$_2$ nanotubes enable integration of conformed hierarchical and blocking layers for enhanced dye-sensitized solar cell efficiency},
author = {Abdelhamid Elzarka and Ning Liu and Imgon Hwang and Mustafa Kamal and Patrik Schmuki},
journal= {arXiv preprint arXiv:2005.01605},
year = {2020}
}