Similarity between optical response kinetics of conducting polymer thin film based gas sensors and electrochromic devices

Chemically deposited polyaniline (PANI) thin films were used as optically active materials in optochemical gas sensors (OGS) as well as in electrochromic devices (ECDs). An electrochemically deposited poly(3-methylthiophene) (P3MT) thin film based ECD was also prepared to be compared to PANI based ECDs. In all these optical devices, the optical response kinetic curves of PANI and P3MT films can be fitted quite well with two terms of the same exponential expression: one faster and one slower. The faster one could be attributed to a rapid specific surface or interface reaction process, and the slower one to a volumetric or bulk diffusion-reaction process. The physical meanings of the fitting parameters come from the Langmuir adsorption theory and Freundlich isotherm in the case of OGS and the Butler-Volmer equation for polymer based ECDs

Photogenerated charge carrier recombination processes in CdS/P3OT solar cells: effect of structural and optoelectronic properties of CdS films

Research and development activities in organic solar cells have been intensified in the last two decades, and the reported energy conversion efficiency in small cell samples is rapidly increased. However, the relation between cell performance and material preparation conditions is not fully understood. In this work charge carrier recombination processes in hybrid poly-3-octylthiophene (P3OT)/cadmium sulfide (CdS) photovoltaic cells were analyzed as a function of structural and optoelectronic properties of chemical bath deposited CdS thin films. The temperature of the bath solution varied between 60 and 80 °C, and the deposition time from 1 to 3 h. Charge carrier recombination times in CdS films were measured with photoconductance decay technique, whereas the same time in P3OT films was estimated by Time-of-Flight method. Charge carrier recombination rates at CdS/P3OT interface were determined by transient photovoltage technique. It is found that CdS films grown at lower solution temperature (60 °C) give a higher charge carrier recombination rate at CdS/P3OT interface and larger short-circuit current density and energy conversion efficiency values in the corresponding solar cells, in comparison with the 80 °C deposited ones. This improvement could come from the reduction of charge carrier trap density inside grains as well as at grain boundaries in lower temperature deposited CdS films

Fabrication of PVDF/PMMA Polymer for Sustainable Energy Harvesting

Abstract: The synthesis of blends that combine properties of two or more polymeric materials is increasingly investigated due to the versatility of the synthesis and its growing potential for many applications, including sustainability. Their characteristics are defined mainly by the synthesis conditions. Therefore, this paper details the synthesis process of easy-to-handle films using mixing method. The procedures and drawbacks found during the preparation of composite films are described. Polymeric compounds formed by the mixture of polyvinylidene fluoride (PVDF) and polymethyl methacrylate (PMMA) are addressed, varying the concentration, and evaluating their impact on the piezoelectric capacity. Films were formed through the spin-coating technique and characterized by optical and holographic microscopes. The results showed that composites with a concentration of 50 wt.% or larger of PVDF in the blend acquire a morphology with a granular appearance, however at lower concentrations they present a homogeneous morphology similar to that of PMMA. A homogeneous distribution of PVDF in the PMMA stands out. However, excessive contents of PMMA are associated to peaks and non-uniformities detected like multicolored regions by digital holography. Controlled strength-strain laboratory tests allowed to evaluate the film blends performance. The results indicate noticeable improvements in voltage output for a composition 70wt% PVDF and 30 wt% PMMA

Caracterización Óptica y Morfológica de Materiales Compuestos de P30T y Nanotubos de Carbono Funcionalizados.

El presente articulo evalúa el efecto de la funcionalización sobre la dispersión de nanotubos de carbono de pared sencilla (SWCNTs, Single Wall Carbono Nanotubes) y deparedmúltiplc (MWCNTs, Multi Wall Carbon Nanotubes) en peliculas compuestas de los nanotubos con poli-3-octiltiofeno (P30T). El método de funcionalización empleado fue mediante el uso de HN03, H2 O2 y el ácido [2-(3-tienil)etil]-fosfónico a bajas concentraciones, perlodos de tratamiento relativamente cortos y aplicación de baja energia de sonicaciÓD. El objetivo de emplear condiciones experimentales leves es lograr funcionalizar a los nanotubos (CNTs) ocasionando daño mfnimo en su estructura. Se observaron mediante TEM y SEM cambios en la moñologia superficial de los nanotubos tratados y de las peHculas compuestas, estos cambios se corroboraron también a través de FTIR.. En las propiedades ópticas de absorbancia de las películas compuestas de SWCNTs-P30T se observó la aparición de nuevas bandas de energia, diferentes a las del P30T pristino

Caracterización óptica y morfológica de materiales compuestos de P3OT y nanotubos de carbono funcionalizados

El presente artículo evalúa el efecto de la funcionalización sobre la dispersión de nanotubos de carbono de pared sencilla (SWCNTs, Single Wall Carbon Nanotubes) y de pared múltiple (MWCNTs, Multi Wall Carbon Nanotubes) en películas compuestas de los nanotubos con poli-3-octiltiofeno (P3OT). El método de funcionalización empleado fue mediante el uso de HNO3, H2O2 y el ácido [2-(3-tienil)etil]-fosfónico a bajas concentraciones, periodos de tratamiento relativamente cortos y aplicación de baja energía de sonicación. El objetivo de emplear condiciones experimentales leves es lograr funcionalizar a los nanotubos (CNTs) ocasionando daño mínimo en su estructura. Se observaron mediante TEM y SEM cambios en la morfología superficial de los nanotubos tratados y de las películas compuestas, estos cambios se corroboraron también a través de FTIR. En las propiedades ópticas de absorbancia de las películas compuestas de SWCNTs-P3OT se observó la aparición de nuevas bandas de energía, diferentes a las del P3OT pristino