Coverage Analysis for the Core/Shell Electrode of Dye-Sensitized Solar Cells

In this study, we established a core/shell (C/S) model that evaluates the surface coverage of an overlayer deposited on nanoparticles in terms of X-ray photoelectron spectroscopy signals of the nanoparticles. We used the model to estimate the coverage of Al 2 O 3 shell layers, which were deposited on the nanoporous TiO 2 electrodes of dye-sensitized solar cells (DSSCs) by atomic layer deposition (ALD), as a function of the number of ALD reaction cycles. The surface coverage increased with the average thickness of the Al 2 O 3 shell layers, indicating that the ALD Al 2 O 3 deposition on the nanoporous electrode was via the island growth mode. The power conversion efficiency of the DSSCs was highest after the first ALD reaction cycle for the Al 2 O 3 shell layers, which had a coverage of 0.25, according to the C/S model. The study shows that, to further improve the PCE, optimization of the ALD Al 2 O 3 deposition condition is required so that the surface coverage of the shell layer can be increased at the first ALD reaction cycle.