Search

Titanium dioxide thin films have been deposited on silicon wafers substrates by an atomic layer deposition (ALD) method. There optical parameters were investigated by spectroscopic ellipsometry and UV/VIS spectroscopy. A material with a refractive index of 2.41 was obtained. Additionally, in a wide spectral range it was possible to reduce the reflection from the silicon surface below 5%. The Raman spectroscopy method was used for structural characterization of anatase TiO2 thin films. Their uniformity and chemical composition are confirmed by a scanning electron microscope (SEM) energy dispersive spectrometer (EDS). [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to improve the efficiency of dye-sensitized solar cells (DSSCs) which present promising low-cost alternative to the conventional silicon solar cells mainly due to comparatively low manufacturing cost, ease of fabrication and relatively good efficiency. One of the undesirable factor in DSSCs is the electron recombination process that takes place at the transparent conductive oxide/electrolyte interface, on the side of photoelectrode. To reduce this effect in the structure of the solar cell, a TiO2 blocking layer (BL) by atomic layer deposition (ALD) was deposited. Design/methodology/approach: Scanning electron microscope, Raman and UV-Vis spectroscopy were used to evaluate the influence of BL on the photovoltaic properties. Electrical parameters of manufactured DSSCs with and without BL were characterized by measurements of current-voltage characteristics under standard AM 1.5 radiation. Findings: The TiO2 BL prevents the physical contact of fluorine-doped tin oxide (FTO) and the electrolyte and leads to increase in the cell's overall efficiency, from 5.15 to 6.18%. Higher density of the BL, together with larger contact area and improved adherence between the TiO2 layer and FTO surface provide more electron pathways from TiO2 to FTO which facilitates electron transfer. Originality/value: This paper demonstrates that the introduction of a BL into the photovoltaic device structure is an important step in technology of DSSCs to improve its efficiency. Moreover, the ALD is a powerful technique which allows for the highly reproducible growth of pinhole-free thin films with excellent thickness accuracy and conformality at low temperature. [ABSTRACT FROM AUTHOR]