Polymerization Catalysis, Flexible Polymer and Nanotechnology

Biography

Biography: Venkata Madhuri

Abstract

In modern years there has been an enormous interest in electrochromic technology, which triggered the designing and fabrication of efficient electrochromic devices (ECD) which work on the phenomena of electrochromism, in which a reversible optical modulation in the materials can be achieved by intercalation/deintercalation of small cations and electrons by the application small electric field. Tungsten trioxide (WO₃) is one among the various EC transition metal oxides recognized as best EC material in thin film form. It exhibits large optical modulation, good durability, stability, low power consumption for the prepared ECDs.

                                 WO₃(Transparent) + xH⁺ + xe^-  ↔ H_xWO₃(Blue)

        In the present work, WO₃ thin films were prepared by electron beam evaporation technique at various oxygen partial pressures (PO₂) ranging from 2x10^-3 to 2x10^-5 mbar and at the substrate temperature of 250 ^oC. The films were deposited onto well cleaned glass, ITO coated glass and silicon substrates. The influence of oxygen partial pressure on the growth, morphology, optical and electrochromic properties have been investigated. The XRD studies revealed that the phase transformation taken place from orthorhombic to monoclinic with respect to PO₂ from 2x10^-3 to 2x10^-5 mbar. The maximum optical bandgap of   3.28 eV was obtained for the films deposited at 2x10^-5 mbar and decreased to 2.66 eV for the films deposited at 2x10^-3 mbar. The coloration efficiency of WO₃ films at the wavelength of 550 nm were found to be 50.84, 29.56 and 24.95 cm²/C for the films deposited in the PO₂ of 2x10^-3, 2x10^-4 and 2x10^-5 mbar respectively.