In thin films solar cells technology, many different materials have been used; however, toxic and expensive materials and techniques have been widely employed up to date. In this work, three different low/non-toxic materials were grown by means simple and cheap techniques.Cd1–xZnxS thin films with Zn concentrations of 0–5 at.% were analyzed. The effect of the addition of different molar Zn concentrations to the reaction mixture on the growth mechanism of Cd1–xZnxS thin films and the influence of these mechanisms on structural, optical and morphological properties of the films has been studied.Cd1–xZnxS thin films were synthesized by chemical bath deposition using an ammonia-free alkaline solution. Microstructural analysis by X-ray diffraction showed that all deposited films grew with hexagonal wurtzite structure and crystallite sizes decreased as the Zn concentration in the film increased. Optical measurements indicated a high optical transmission between 75 % and 90 % for wavelengths above the absorption edge. Band gap value increased from 2.48 eV to 2.62 eV, and the refractive index values for Cd1–xZnxS thin films decreased as the Zn increased. These changes in films and properties are related to a modification in growth mechanism of the Cd1–xZnxS thin films, with the influence of Zn(OH)2 formation being more important as Zn in solution increased.Characterization of ZnS thin films deposited by chemical bath in a non-toxic alkaline solution is reported. The effect of deposition technique (growth in several times) on the properties of the ZnS thin film was studied. The films exhibited a high percentage of optical transmission (greater than 80 %); as the deposition time increased a decreasing in the band gap values from 3.83 eV to 3.71 eV was observed. From chemical analysis, the presence of ZnS and Zn(OH)2 was identified and X-ray diffraction patterns exhibited a clear peak corresponding to ZnS hexagonal phase (103) plane, which was confirmed by electron diffraction patterns. From morphological studies, compact samples with well-defined particles, low roughness, homogeneous and pinhole-free in the surface were observed.On the other side, characterization of one-step electrodeposited CuInS2 thin films is reported. The effect of the complexing agent C8H5KO4 on the reduction potential of metallic ions, as well as the annealing conditions to avoid film oxidation was studied. From polarization curves, it was observed that C8H5KO4 is an appropriate complexing agent to bring the reduction potential of Cu2+ closer to In3+. XRD patterns showed films with hexagonal structure and no peaks attributed to oxide phases were observed, under a 95 % N2 + 5 % H2 atmosphere and using a carbon holder. However, others two weak peaks associated to Cu7S4 phase were identified. The CuInS2 thin films exhibited a band gap value of 1.50 eV, low optical transmission in the visible range, p-type conductivity and a charge carrier concentration of 2.3 × 10-18 cm-3. Finally, from morphological and chemical analysis, it was possible to observe a compact morphology and free of pinholes surface with a composition close to the stoichiometric one. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished
| Identifer | oai:union.ndltd.org:ulb.ac.be/oai:dipot.ulb.ac.be:2013/247379 |
| Date | 27 October 2015 |
| Creators | Rodríguez Rodríguez, Carlos |
| Contributors | Delplancke, Marie-Paule, Carrasco, Claudia, Degrez, Marc, Dubois, Frank, Olivier, Marie-Georges, Ramam, Koduri |
| Publisher | Universite Libre de Bruxelles, University of Concepción, Faculty of Engineering, Department of Materials Engineering - Doctor en Ciencia e Ingeniería de Materiales, Université libre de Bruxelles, Ecole polytechnique de Bruxelles – Chimie et Science des Matériaux, Bruxelles |
| Source Sets | Université libre de Bruxelles |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis, info:ulb-repo/semantics/doctoralThesis, info:ulb-repo/semantics/openurl/vlink-dissertation |
| Format | 3 full-text file(s): application/pdf | application/vnd.openxmlformats-officedocument.wordprocessingml.document | application/pdf |
| Rights | 3 full-text file(s): info:eu-repo/semantics/closedAccess | info:eu-repo/semantics/openAccess | info:eu-repo/semantics/restrictedAccess |
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