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| Author(s): |
Lucas Marinho Nobrega de Assis
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT) |
| Defense date: | 2016-05-11 |
| Examining board members: |
Agnieszka Joanna Pawlicka Maule;
Patrice Baldeck;
Andréa Simone Stucchi de Camargo Alvarez Bernardez;
Carla Cristina Schmitt Cavalheiro;
Maria Manuela da Silva Pires da Silva
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| Advisor: | Agnieszka Joanna Pawlicka Maule |
| Abstract | |
This work presents the results of the preparation and characterization of electrochromic devices (ECDs) containing a thin film of Prussian blue (PB) as electrochromic layer, CeO2-TiO2 as a counter electrode and electrolytes based on polymers containing glycerol, formaldehyde, and γ-butyrolactone. Thin films of Prussian blue were prepared by galvanostatic electrodeposition method and used for the assembly of electrochromic devices with varying polymer composition of electrolytes. The thin films were characterized by charge density measurements, cyclic voltammetry, transmittance in the UV-Vis, and morphological analyzes such as atomic force microscopy (AFM) and scanning electron microscopy (SEM). Moreover, there were subjected to ellipsometry, thickness, contact angle, and coloring efficiency measurements. The electrodeposited film of 300 s had charge density of 1.62 mC.cm-2 and 0.98 of reversibility with roughness of 17.7 nm and thickness of 315 nm via ellipsometry and 216 nm via profilometry. The calculated color efficiency was 131.4 cm2.C-1 and the contact angle values and surface free energy were calculated. The voltammetric analyzes of thin films showed characteristic peaks of oxidation and reduction processes and spectroscopic analysis showed 71.6% transmittance variation at 686 nm in 1 mol.L-1 KCL electrolyte solution. ECD were prepared and characterized, using electrolytes such as commercial gelatin with LiClO4 salt; poly (vinyl butyrate) (PVB) with ion pair LiI/I2; PVB with LiClO4; PVB with ion pair LiI/I2 + disperse red; agar with LiClO4; agar with Eu(CF3SO3)3 salt; DNA with LiClO4; DNA with Er(CF3SO3)3 salt; pectin with LiClO4; HPC with acetic acid; HPC with LiClO4 and PVDF LiClO4. The best results of charge density of 8.5 and 10.1 mC.cm-2 were obtained for devices with HPC electrolytes and pectin, both with LiClO4 salt. Cyclic voltammetry of the studied samples revealed anodic and cathodic peaks relating to the extraction and insertion of lithium ions and/or protons and electrons in the PB film. The transmittance at 686 nm analysis between the colored state and discolored windows showed values of 40.2% for the window containing electrolyte of gelatin with LiClO4 and 35.2% for the window with agar and Eu(CF3SO3) salt. Furthermore, the stability of the devices was also recorded revealing the duration between 400-2200 chronoamperometric cycles, depending on the used electrolyte. The results show that the windows studied in this work are potential candidates for electrochromic devices applications. (AU) | |
| FAPESP's process: | 12/14103-3 - Electrochromic devices with Prussian blue and electrolytes based on natural and/or synthetic macromolecules |
| Grantee: | Lucas Marinho Nóbrega de Assis |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |