Solution-free and catalyst-free synthesis of ZnO-based nanostructured TCOs by PED and vapor phase growth techniques

Abstract

Zinc oxide (ZnO) is one of the most promising materials for realizing three-dimensional (3D) nanostructured transparent conducting oxides (TCOs) on large scale, because it is cheap, it can be modified with large concentrations of trivalent elements (such Al, Ga or In) and it is characterized by good electron mobility, wide bandgap and visible-range transparency. But, above all, it can be easily obtained in the form of different nanostructures with a large number of growth techniques. A solution-free and catalyst-free approach has been explored here by the vapor phase synthesis of vertically aligned ZnO nanorods on ZnO:Al (AZO) films grown by pulsed electron deposition (PED). The obtained nanostructured TCOs resulted to be homogeneous on large areas and easily patternable by means of mechanical masks. The morphology, crystalline structure, electrical and optical properties of the obtained samples have been characterized in depth. The possible use of such a nanostructured TCO in excitonic (e.g. DSSC) or low-reflectivity traditional solar cells is discussed.

Zn vacancy induced green luminescence on non-polar surfaces in ZnO nanostructures

“…1e) depicts the diffraction pattern of the ZnO polycrystalline substrate, with strong orientation along the polar [0001] direction of the wurtzite structure and with minor contribution of other directions37: the diffraction peaks at about 31.7°, 34.4°, 36.1°, 62.8° are ascribable to the (10 1 0), (0002), (10 1 1) and (0004) planes, respectively, in good agreement with previous results38.…”

“…51 directly on the ZnO seed layer obtained by pulsed electron deposition38. Commercial Zn (powder, Sigma Aldrich, 4.5N) is used as source material after a smooth etching in diluted HCl.…”

Interior-architectured ZnO nanostructure for enhanced electrical conductivity via stepwise fabrication process

“…In the case of the NR nanoline, its responsivity was almost as low as the TA nanoline. This result can be attributed to increased carrier scattering by the complex path in NR nanolines as well as increased grain boundaries due to augmented junctions between nanorods [28]. …”

Tuning electrical properties of hierarchically assembled Al-doped ZnO nanoforests by room temperature Pulsed Laser Deposition

“…organic or hybrid next generation solar cells) AZO must meet novel requirements which are not limited to optical transparency and electrical conductivity, but include light scattering, large surface area and compatibility with flexible polymer substrates (i.e. no deposition or post-deposition treatments at high temperature) [4][5][6][7].…”