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Here, we report room temperature deposition of nickel oxide (NiO) thin films on silicon and glass substrates by direct current (dc) magnetron sputtering using a metallic nickel target. The effect of sputtering power (20 W, 25 W, and 30 W) on the thin films, their surface scaling, fractal dimension, and optical properties are extensively investigated. Autocorrelation and height–height correlation functions were applied to AFM images to extract deep insights about the thin films' surfaces. Fractal dimension (D f) was extracted through the power spectral density (PSD) function. Various scaling exponents, including α, β, and 1/z, of the NiO film's surface were independently observed. The local roughness exponent, α, was approximately 0.81 for films deposited with 20 W sputtering power and decreased to 0.71 with higher sputtering power. The interface width (σ) scales with sputtering power (Sp) as ∼ Spβ, with a growth exponent (β) value of 1.17. The lateral correlation length (ξ) follows as ∼ Sp1/z with a 1/z value of 0.703. Additionally, optical parameters were recorded through UV–Vis. optical spectroscopy, and an attempt was made to correlate them with fractal parameters (D f & α). Optical absorption (reflection) increased (decreased) with increasing D f values. The minimum (maximum) reflection (absorption) was observed on the roughest surface (D f = 2.29). The calculated band gap decreased with increasing fractal dimension. This investigation suggests that sputtered surfaces with minimal reflectivity, band gap, and enhanced light-absorbing capacity could potentially be used as active solar layers for advanced optoelectronic devices. [ABSTRACT FROM AUTHOR]

Here we report, the room temperature deposition of silver (Ag) thin films on silicon, glass and silicon solar cell substrates by magnetron sputtering. The effect of thickness on the deposited thin films and their morphological, fractal, optical and solar cell parameters have been extensively investigated. AFM results show that the Ag thin films are composed of different-size of nano-grains and the grain size increases with increasing thickness. Mono-fractal parameters, namely fractal dimension (Df) and Hurst exponent (H), were determined from the power spectral density function. X-ray photoelectron spectroscopy studies indicate that the deposited samples exhibit the presence of oxidation state of Ag (0) in thin films, confirming the stable structure. The optical analysis shows that the transmittance of the deposited thin films decreases with increasing thickness, on the other hand, the silver thin film with thickness of 20 nm shows surface Plasmon resonance (SPR) at 436 nm. Current-voltage (I–V) curves were measured in dark and under illumination mode at standard testing conditions, i.e., 300K, 1000 W/m2 and 1.5 AM global using a solar simulator. These measurement studies indicate that thicknesses are effectively impacts on photovoltaic performance. The calculated values of change in solar efficiency (Δ η) are 0.26, −0.20, −0.76 and −6.88 % for thin films with nominal thickness 0.5, 1, 2 and 20 nm respectively. • Ag thin films were deposited by magnetron sputtering technique. • The influence of ultrathin layers on the fractal dimensions of Ag films was studied. • The influence of ultrathin layers on the optical properties of Ag films was studied. • The influence of ultrathin layers on the solar cell performance have been explored. • The influence of optical parameters viz. reflection, plasmonic on solar cell efficiency have been studied. [ABSTRACT FROM AUTHOR]

We performed density-functional-theoretical calculations of the silanediol-like molecules adsorbed on (TiO 2) 20 tetrahedral-like clusters. We study the adsorption on the triangular face of the (TiO 2) 20 clusters in two different sites (C e n t e r and E d g e). Our results suggest that the band gap of the (TiO 2) 20 nano-clusters can be controlled (tune or adjust) changing the length of the molecule as well as the terminal element within the molecule chain. The adsorption energy or functionalization energy of the cluster is almost independent of the number of atoms, presenting only a slight increase with the number of atoms in the adsorbed molecular chain. We also analyze the dependence of the gap with iso-electronic final monomer for a few selected cases. • DFT theoretical calculations of Transition Metal Oxides with adsorbed molecules. • Possible way to control the gap of Transition Metal clusters by molecules. • Dependence of the gap on the ending monomer of the adsorbed molecules. [ABSTRACT FROM AUTHOR]