Analysis by finite element calculations of light scattering in laser-textured AZO films for PV thin-film solar cells

In the thin-film photovoltaic industry, to achieve a high light scattering in one or more of the cell interfaces is one of the strategies that allow an enhancement of light absorption inside the cell and, therefore, a better device behavior and efficiency. Although chemical etching is the standard method to texture surfaces for that scattering improvement, laser light has shown as a new way for texturizing different materials, maintaining a good control of the final topography with a unique, clean, and quite precise process. In this work AZO films with different texture parameters are fabricated. The typical parameters used to characterize them, as the root mean square roughness or the haze factor, are discussed and, for deeper understanding of the scattering mechanisms, the light behavior in the films is simulated using a finite element method code. This method gives information about the light intensity in each point of the system, allowing the precise characterization of the scattering behavior near the film surface, and it can be used as well to calculate a simulated haze factor that can be compared with experimental measurements. A discussion of the validation of the numerical code, based in a comprehensive comparison with experimental data is included.

Effects of unique ion chemistry on thin-film growth by plasma–surface interactions

Plasma processing is a standard industrial method for the modification of material surfaces and the deposition of thin films. Polyatomic ions and neutrals larger than a triatomic play a critical role in plasma-induced surface chemistry, especially in the deposition of polymeric films from fluorocarbon plasmas. In this paper, low energy CF3+ and C3F5+ ions are used to modify a polystyrene surface. Experimental and computational studies are combined to quantify the effect of the unique chemistry and structure of the incident ions on the result of ion-polymer collisions. C3F5+ ions are more effective at growing films than CF3+, both at similar energy/atom of ≈6 eV/atom and similar total kinetic energies of 25 and 50 eV. The composition of the films grown experimentally also varies with both the structure and kinetic energy of the incident ion. Both C3F5+ and CF3+ should be thought of as covalently bound polyatomic precursors or fragments that can react and become incorporated within the polystyrene surface, rather than merely donating F atoms. The size and structure of the ions affect polymer film formation via differing chemical structure, reactivity, sticking probabilities, and energy transfer to the surface. The different reactivity of these two ions with the polymer surface supports the argument that larger species contribute to the deposition of polymeric films from fluorocarbon plasmas. These results indicate that complete understanding and accurate computer modeling of plasma–surface modification requires accurate measurement of the identities, number densities, and kinetic energies of higher mass ions and energetic neutrals.

Improving the photoactivity of bismuth vanadate thin film photoanodes through doping and surface modification strategies

Currently, one of the most attractive and desirable ways to solve the energy challenge is harvesting energy directly from the sunlight through the so-called artificial photosynthesis. Among the ternary oxides based on earth–abundant metals, bismuth vanadate has recently emerged as a promising photoanode. Herein, BiVO4 thin film photoanodes have been successfully synthesized by a modified metal-organic precursor decomposition method, followed by an annealing treatment. In an attempt to improve the photocatalytic properties of this semiconductor material for photoelectrochemical water oxidation, the electrodes have been modified (i) by doping with La and Ce (by modifying the composition of the BiVO4 precursor solution with the desired concentration of the doping element), and (ii) by surface modification with Au nanoparticles potentiostatically electrodeposited. La and Ce doping at concentrations of 1 and 2 at% in the BiVO4 precursor solution, respectively, enhances significantly the photoelectrocatalytic performance of BiVO4 without introducing important changes in either the material structure or the electrode morphology, according to XRD and SEM characterization. In addition, surface modification of the electrodes with Au nanoparticles further enhances the photocurrent as such metallic nanoparticles act as co-catalysts, promoting charge transfer at the semiconductor/solution interface. The combination of these two complementary ways of modifying the electrodes has resulted in a significant increase in the photoresponse, facilitating their potential application in artificial photosynthesis devices.

Photovoltaic mechanisms in polycrystalline thin film silicon solar cells : quarterly technical progress report no. 1, July 30-October 31, 1980 /

"Work Performed Under Contract No. AC02-77CH00178."

Development of copper sulfide/cadmium sulfide thin-film solar cell s : third technical progress report, January 13 - April 12, 1980 /

"Work Performed Under Contract No. AC02-77CH00178."

Development of copper sulfide/cadmium sulfide thin film solar cell s : fourth technical progress report, April 13 - July 12, 1980 /

"Work Performed Under Contract No. AC02-77CH00178."

Thin film polycrystalline silicon solar cells : technical progress quarterly report no. 3 for March 25 - June 24, 1980 /

"Work Performed Under Contract No. AC02-77CH00178."

Thin-film polycrystalline silcon solar cells : quarterly technical progress report no. 3 for period April 1 - June 30, 1980 /

"Work Performed Under Contract No. AC02-77CH00178."

Thin film polycrystalline silicon solar cells : first technical progress report for April 15 - July 15, 1980.

"Work Performed Under Contract No. AC02-77CH00178."

Thin film polycrystalline silicon solar cells : second technical progress report for July 15 - October 15, 1980.

"Work Performed Under Contract No. AC02-77CH00178."

Indium phosphide/cadmium sulfide thin-film solar cells : quarterly report for period July - October 1980 /

"Work Performed Under Contract No. AC02-77CH00178."

MIS and P/N junction solar cells on thin-film polycrystalline silicon /

"Work Performed Under Contract No. EG-77-C-01-4042."

Electrochemical photovoltaic cells CdSe thin film electrodes : final report, June 1979-June 1980 /

"Contract No. AC02-77CH00178."

Indium phosphide/cadmium sulfide thin-film solar cells : final report for period May 1979 - July 1980 /

"Contract No. AC02-77CH00178."