8 research outputs found
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
Similarity between optical response kinetics of conducting polymer thin film based gas sensors and electrochromic devices.
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聽掳C, and the deposition time from 1 to 3聽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聽掳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聽掳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
Caracterizaci贸n 脫ptica y Morfol贸gica de Materiales Compuestos de P30T y Nanotubos de Carbono Funcionalizados.
El presente articulo eval煤a el efecto de la funcionalizaci贸n sobre la dispersi贸n de nanotubos de carbono de pared sencilla (SWCNTs, Single Wall Carbono Nanotubes) y deparedm煤ltiplc (MWCNTs, Multi Wall Carbon Nanotubes) en peliculas compuestas de los nanotubos con poli-3-octiltiofeno (P30T). El m茅todo de funcionalizaci贸n empleado fue mediante el uso de HN03, H2 O2 y el 谩cido [2-(3-tienil)etil]-fosf贸nico a bajas concentraciones, perlodos de tratamiento relativamente cortos y aplicaci贸n de baja energia de sonicaci脫D. El objetivo de emplear condiciones experimentales leves es lograr funcionalizar a los nanotubos (CNTs) ocasionando da帽o mfnimo en su estructura. Se observaron mediante TEM y SEM cambios en la mo帽ologia superficial de los nanotubos tratados y de las peHculas compuestas, estos cambios se corroboraron tambi茅n a trav茅s de FTIR.. En las propiedades 贸pticas de absorbancia de las pel铆culas compuestas de SWCNTs-P30T se observ贸 la aparici贸n de nuevas bandas de energia, diferentes a las del P30T pristino
Caracterizaci贸n 贸ptica y morfol贸gica de materiales compuestos de P3OT y nanotubos de carbono funcionalizados
El presente art铆culo eval煤a el efecto de la funcionalizaci贸n sobre la dispersi贸n de nanotubos de carbono de pared sencilla (SWCNTs, Single Wall Carbon Nanotubes) y de pared m煤ltiple (MWCNTs, Multi Wall Carbon Nanotubes) en pel铆culas compuestas de los nanotubos con poli-3-octiltiofeno (P3OT). El m茅todo de funcionalizaci贸n empleado fue mediante el uso de HNO3, H2O2 y el 谩cido [2-(3-tienil)etil]-fosf贸nico a bajas concentraciones, periodos de tratamiento relativamente cortos y aplicaci贸n de baja energ铆a de sonicaci贸n. El objetivo de emplear condiciones experimentales leves es lograr funcionalizar a los nanotubos (CNTs) ocasionando da帽o m铆nimo en su estructura. Se observaron mediante TEM y SEM cambios en la morfolog铆a superficial de los nanotubos tratados y de las pel铆culas compuestas, estos cambios se corroboraron tambi茅n a trav茅s de FTIR. En las propiedades 贸pticas de absorbancia de las pel铆culas compuestas de SWCNTs-P3OT se observ贸 la aparici贸n de nuevas bandas de energ铆a, diferentes a las del P3OT pristino