Morphology, Electrical and Optical Properties of Cu Nanostructures Embedded in AZO: A Comparison between Dry and Wet Methods

Abstract

Herein, Cu nanostructures are obtained by solid-state dewetting of 9 nm copper layer (dry) or by ablating copper target, using a nanosecond pulsed laser at 1064 nm, in acetone and isopropyl alcohol (wet). The Cu nanostructures are embedded in aluminum-doped zinc oxide layer. Then, the electrical, optical, and morphological properties of the two kinds of systems, as a function of their synthesis parameters, are investigated. The aim is to compare the two fabrication methods and select the main conditions to achieve the best system for photovoltaic applications. The main differences, exhibited by the wet and dry processes, were in the shape and size of the Cu nanostructures. Dewetting in nitrogen produces faceted nanoparticles, with an average size below 150 nm, while laser ablation originates spherical and smaller nanoparticles, below 50 nm. Dry system underwent to thermal annealing, which improves the electrical properties, compared to the wet system, with a sheet resistance of 103 vs. 106 Ω/sq, respectively; finally, the dry system shows a maximum transmittance of 89.7% at 697 nm, compared to the wet system in acetone, 88.4% at 647 nm, as well as in isopropyl alcohol, 86.9% at 686 nm. Moreover, wet systems show higher transmittance in NUV.

Plasmonic and Conductive Structures of TCO Films with Embedded Cu Nanoparticles

“…If we considered the first configuration (Glass/AZO bottom/Cu (as deposited or + thermal annealing)/IZrO top), as expected, after a thermal annealing we observed an improvement in the AZO bottom R sh of up to three orders of magnitude until about 2 × 10 3 Ω/sq at 400 °C [ 40 ]. Beyond 400 °C, no significant improvement was observed.…”

“…Figure 6 a,b and Table 3 show a comparison among the PCSs with the best optical and electrical properties produced in this work and in our previous work [ 40 ] for PCSs constructed using the wet procedure with AZO as the top and bottom layers.…”

Monte Carlo Approach to the Evaluation of Nanoparticles Size Distribution from the Analysis of UV-Vis-NIR Spectra

“…The experimental extinction spectra of the copper solutions (dotted lines in Figure 5) present the typical copper plasmonic peak at ∼600 nm [4,11] and a strong absorbance in the UV region that goes to zero in the IR. The spectra of copper NPs produced in methanol and ethanol present also a hint of a large shoulder between 600 and 800 nm and a plateau between 400 and 500 nm, suggesting the presence of agglomerates or particles in the order of 100 nm radius.…”

“…In particular, copper and gold NPs are widely used in plasmonic devices due to their optical properties in the visible light range. The UV-Vis-NIR spectra of Cu and Au NPs present a typical peak, called plasmonic peak, in a specific wavelength range, depending on the material, that can be used for various devices and applications [1][2][3][4][5][6][7][8][9][10].…”