Thermal Dependence of Optical Parameters of Thin Polythiophene Films Blended with PCBM

The main purpose of this work is to show the thermal dependence of the refractive and extinction indices of conjugated polymer films used in optoelectronics devices. Herein, we present the results of optical investigations performed for the following polymers: poly(3-hexylthiophene) (P3HT), poly(3-octylthiophene) (P3OT), and their blends with [6,6]-phenyl C61 butyric acid methyl ester (PCBM). For our analysis, we chose well-known polythiophenes such P3HT and P3OT, often used in photovoltaic cells. Our addition of PCMB to the polythiophenes allows their conversion efficiency to be increased. This paper presents the results of our investigation determining the spectral dispersion of optical constants in a wavelength range of 190–1700 nm by using spectroscopic ellipsometry (SE). Furthermore, we show the temperature dependence of the refractive indices of polythiophene films for a heating and a cooling process in the temperature range 25–130 °C. Additionally, thermo-optic coefficients and an optical gap were established and are presented in the paper, followed by a discussion on the conditions of the thermal stability of polythiophene blends and reversibility issues in thermal processes. Our paper presents a new and fresh analysis of depolarization beams after their reflection from the studied films. The paper presents the results of thermo-optical studies of polymer blends which have not been included in previously published works

Recognizing steel elements with BRDF and k-nearest neighbors

The paper deals with analysis of recognition of surface quality with reflective structures. Such surfaces are common in metallic materials cut using a saw or polished. There are no easy methods to identify such elements after machining. This issue is crucial in the industry for quality control as recognition of the elements, for instance after failure, allows for a detailed study of their manufacturing process. Firstly, six cuboid steel elements were obtained from a larger beam with a circular saw. Then, the bidirectional reflection distribution function (BRDF) was obtained for each element 3 times. The BRDF profiles were used in custom recognition software based on the K-nearest neighbors algorithm. In total, 140 variants of the classifier were tested and analyzed. Additionally, each variant was solved 200 times with different splits of the dataset. The results showed a high multiclass accuracy in all considered variants of the algorithm, with multiple variants achieving 100% accuracy. This level of performance was attained with only 1 to 2 training samples per class. Its low numerical complexity, easy experimental procedure, and “one-shot” nature allow for fast recognition, which is crucial in industrial applications

The effect of molding conditions on the quality of geopolymer surfaces

The presented work describes the method of measuring surface topography with application of BRDF (bidirectional reflectance distribution function), ellipsometry and spectrophotometry. This non-contact method enables measurement and analysis of large area surfaces, such as plasters and facades. A standard method of topography analysis does not describe sufficiently all of the interesting features. The visual aspect of the surface evaluation is very important from the functional and utilitarian point of view. The proposed methods of surface analysis enable not only the quantitative evaluation but also indirectly the qualitative properties (visual aspects)

Scattering Phenomena in Porous Sol-Gel-Derived Silica Films

This paper presents the results of investigations of optical scattering phenomena in porous silica films. SiO(2)films were prepared by the sol-gel method and deposited on polished silicon wafers by the dip-coating technique. Fabricated films were studied using integrating sphere reflectometry, spectroscopic ellipsometry, atomic force microscopy, scanning electron microscopy, and angular resolve scattering. The spectral characteristics of the refractive and extinction indices and scattering extinction coefficients are presented. Additionally, the depolarization of reflected beam from samples was measured. The tested films were characterized by a thickness of 500 to 900 nm, a porosity of 50%, and refractive indices of less than 1.24. The observed depolarization of light reflected from SiO(2)films resulted from surface and bulk scattering. This phenomenon resulted from the presence of surface and closed pores located in the bulk of SiO(2)film

The Optical and Thermo-Optical Properties of Non-Stoichiometric Silicon Nitride Layers Obtained by the PECVD Method with Varying Levels of Nitrogen Content

In this paper, we investigated the optical and thermo-optical properties of a-SiNx:H layers obtained using the PECVD technique. SiNx:H layers with different refractive indices were obtained from silane and ammonia as precursor gases. Surface morphology and chemical composition studies were investigated using atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and energy dispersive spectrometry methods. Spectroscopic ellipsometry was used to determine the optical indexes, thicknesses and optical bandgap of the films. The main purpose was to identify the thermo-optical characteristics of layers with different refractive indexes. Thermo-optical studies were performed to determine the temperature hysteresis of optical parameters. These measurements showed that after annealing up to 300 °C and subsequent cooling, the value of optical parameters returned to the initial values