Physical Investigations on Molybdenum Trioxide Thin Films

Abstract

Chromogenic materials are a particular class of materials that change the spectral characteristics in the presence of suitable external stimuli; like voltage, temperature, pressure etc. These materials are at the core of the development of efficient Chromogenic devices. These devices found applications in various areas such as heat-sensitive smart window, energy-harvesting, automotive and textile industries, Photochromic lenses, camouflage etc. Considering the various societal applications of such devices, the development of such materials is in demand. In general, these adoptive smart Chromogenic materials broadly categorised into electrochromic, photochromic and thermochromic materials. Among various chromogenic materials like WO3, VO2 liquid crystals etc., Molybdenum trioxide (MoO3) is one of the fascinating chromogenic material due to its unique layered structure, thermodynamically stable orthorhombic and#945;-phase and formation of multiple oxidation state. The performance of device depends on the structure and physical properties which is the function of deposition techniques and parameters. Hence, the specific control on the deposition parameters is necessary for achieving of the desired characteristics of the device. The present thesis describes the characteristics of thermally grown and Pulsed Laser Deposited MoO3 thin films for developing the electrochromic and photochromic devices. Thermal deposition technique is found to be used to deposit thin films, for large scale area having the moderate thin film quality. However, the film grown by the thermal deposition suffer drawback like poor step coverage, lower throughput, adherence etc. To get the good quality thin film growth at the optimum deposition condition and required parameter, the Pulsed laser deposition (PLD) technique is reported to be superior deposition techniques. PLD provide clean and uniform crystalline transition metal oxide thin films, even at lower substrate temperature which prerequisite for various devices.