This review is devoted to the angular selectivity that can be obtained in thin films prepared under conditions such that they contain inclined absorbing regions of sizes much smaller than the wavelength of visible light. The films are of considerable interest as window coatings for energy-conscious architecture and, potentially, in the automotive sector. The theoretical basis for modelling the optical properties is presented, comprising rigorous bounds on the dielectric function, effective medium theories pertinent to different microgeometries and equations for treating the optics of anisotropic thin films. Experimental data are reported for films made by oblique-angle evaporation of Cr and for reactive and non-reactive oblique-angle sputtering of Cr, Al, Ti and W. The highest angular selectivity was obtained with evaporated Cr, whereas the highest luminous transmittance, combined with some angular selectivity, was found with reactively sputtered Al. Films made from Ti showed angular selectivity mainly in the infrared, whereas films made from W could display angular selective electrochromism. Samples of several types were subjected to elaborate theoretical analysis using effective-medium theories and it was seen that theory and experiment could be reconciled using plausible parameters to specify the microstructures of the films. Thus it appears that the angular, spectral and polarization dependences of obliquely deposited films can be understood, at least approximately, in terms of conceptually simple theoretical models.

https://iopscience.iop.org/article/10.1088/0022-3727/30/15/001/pdf

Angular selective window coatings: theory and experiments

High-throughput computational and experimental techniques have been used in the past to accelerate the discovery of new promising solar cell materials. An important part of the development of novel thin film solar cell technologies, that is still considered a bottleneck for both theory and experiment, is the search for alternative interfacial contact (buffer) layers. The research and development of contact materials is difficult due to the inherent complexity that arises from its interactions at the interface with the absorber. A promising alternative to the commonly used CdS buffer layer in thin film solar cells that contain absorbers with lower electron affinity can be found in β-In2S3. However, the synthesis conditions for the sputter deposition of this material are not well-established. Here, In2S3 is investigated as a solar cell contact material utilizing a high-throughput combinatorial screening of the temperature-flux parameter space, followed by a number of spatially resolved characterization tech...

Combinatorial Reactive Sputtering of In2S3 as an Alternative Contact Layer for Thin Film Solar Cells

Effect of precursor concentration on physical properties of nebulized spray deposited In2S3 thin films

Optical, electrical conduction and dielectric properties of TlGaSe2 layered single crystal

New approach to removal of hazardous Bypass Cement Dust (BCD) from the environment: 20Na2O-20BaCl2-(60-x)B2O3-(x)BCD glass system and Optical, mechanical, structural and nuclear radiation shielding competences

Structural and optical properties of nanocrystalline aluminum phthalocyanine chloride thin films

Crystal structure and optical absorption investigations on β-In2S3 thin films

Characterization and photovoltaic performance of organic device based on AlPcCl/p-Si heterojunction

The ternary composition InSbSe3 was synthesized by direct fusion of the stoichiometric quantities of two binary components Sb2Se3 and In2Se3 in an evacuated silica tube. The structural properties of InSbSe3 in its powder and thin film forms were investigated by X-ray. Analysis of X-ray diffractograms showed that the fine powder of InSbSe3 as well as thin films annealed at 423 and 473 K for 1 h are all of polycrystalline triclinic structure with unit cell parameters: a=6.032 A, b=7.040 A, c=12.186 A, α=95.783°, β=51.808°, γ=95.852° and unit cell volume of 402.496 A3. The refractive index, n, and the extinction coefficient, k, of the as-deposited thin films before and after annealing were determined for samples of different thicknesses (114–267 nm) in the spectral range 500–2500 nm. The spectral behaviour of n showed anomalous dispersion in the region of the fundamental absorption edge. The value of the high-frequency dielectric constant (e∞) was obtained as 8.8 for the as-deposited thin films can be explained on the basis of the single oscillator model. The optical constants and the dielectric constant of the thin films were all affected by annealing temperature. The existing allowed optical transitions in the as-deposited thin films as well as annealed thin films were found to be indirect. The indirect energy gap was decreased from 1.46 eV for as-deposited thin films to 1.29 and 1.16 eV as the films were annealed at 423 and 473 K for 1 h, respectively.

B.A. Khalifa

Papers

Structural and optical properties of nanocrystalline aluminum phthalocyanine chloride thin films

Crystal structure and optical absorption investigations on β-In2S3 thin films

Characterization and photovoltaic performance of organic device based on AlPcCl/p-Si heterojunction

Temperature dependence of the structural and optical properties of thermally vacuum evaporated InSbSe3 thin films

Gamma radiation-induced changes on the structural and optical properties of aluminum phthalocyanine chloride thin films