Optical path difference behind of spectacular game of light

AbstractThis work reports, in a general frame concerning the scientific explanations of wonderful effects from the daily life, on the physical basis behind the colorful images observed at the surface of various transparent films. Accordingly, a deeper view inside of the related interference phenomena is provided, along with a new didactical approach. The concept of interference of light is developed and the optical path difference is introduced as a crucial parameter in explaining the formation of the interference patterns. Particularization is done in case of thin film interference, explaining so the spectacular game of colors on the surface of transparent films, observed in nature

Optical and morphological properties of thermally vacuum evaporated cdte thin films for photovoltaic apllications

International audienc

Oxide/Metal/Oxide Transparent Electrodes for Plastic Electronics and Plastic Solar Cells

Date du colloque : 08/2012International audienc

Optical and Morphological Studies of Thermally Vacuum Evaporated ZnSe Thin Films

Zinc selenide (ZnSe) thin films were deposited on optical glass substrates using thermal vacuum evaporation, by sublimation of zinc selenide powder from a single quartz crucible heated at 600 degrees C. The substrates temperatures were maintained constant during deposition at 220 degrees C. All the samples were subjected to post - deposition thermal treatments in the same deposition chamber, at 250 degrees C for 20 minutes. AFM and SEM studies confirmed that post - deposition annealing improved the grains growth and their distribution over the entire surface of the film. Optical constants (refraction indices and extinction coefficients) of semiconducting ZnSe thin films were measured by spectroscopic ellipsometry in the range of 190 nm to 500 nm. Optical measurements were completed with the spectral dependencies of transmission and absorption using a double beam UV - VIS spectrophotometer. The values for optical bandgaps calculated from the absorption spectra were found to be around 2.7 eV. All these results lead to the conclusion, that ZnSe thin films are good candidates to replace the conventional CdS thin films used as n-type window layers in the thin film heterojunction solar cells

Study of physical properties of some transparent oxides semiconductors obtained by thermal oxidation of metallic thin films

Date du colloque : 08/2013International audienc

On the properties of ITO, ZnO, ZnO:Al and NiO thin films obtained by thermal oxidation

Date du colloque : 10/2014International audienc

The influence of LiF layer abd ZnO nanoparticels addings on the performances of flexible photovoltaic cells based on polymer blends

International audienceFlexible organic solar cells were successfully prepared using spin-coating technique on PET substrates covered with a thick layer of ITO. The goal of this study is to identify the effects of the LiF layer and ZnO nanoparticles mixing in PEDOT:PSS solution and to compare the photovoltaic properties of these „customized” cells PET/ITO/PEDOT:PSS + ZnO nanoparticles/P3HT:PCBM(1:1)/Al, PET/ITO/PEDOT:PSS + ZnO nanoparticles/P3HT:PCBM(1:1)/LiF/Al, with ones of the “conventional” structures, PET/ITO/PEDOT:PSS/P3HT:PCBM(1:1)/Al. The thickness of the LiF layer, deposited by thermal vacuum evaporation, was two nanometers. Composite samples were prepared by adding ZnO nanoparticles into PEDOT:PSS solution, followed by ultrasonication. I-V characteristics were measured in dark and under A.M.1.5 conditions for all samples immediately and after one month from the preparation date. The action spectra measurements revealed that the structures which have a nanometric LiF layer are more stable than those without. Photoelectrical measurements indicate that the ZnO nanoparticles have a positive influence on the conversion efficiency and also to reduce the serial resistance of the structure

Electrical and optical properties of Transparent Oxide/Metal/Oxide MultilayerFilms Deposited on Glass and PET substrates

Date du colloque : 10/2012International audienc