بررسي خواص الكتروكروميكي لايه هاي نازك تنگستن اكسيد (WO3) و تنگستن اكسيد آلايش يافته با پالاديم (WO3-Pd)

چكيده انگليسي :

122 Investigation of Electrochromic Properties of Tungsten Oxide WO3 Pd Doped Tungsten Oxide WO3 Pd Thin Films Shirin Hajian s hajian@ph iut ac ir Date of Submission 2015 03 05 Department of Physics Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Dr Hadi Salamati Salamati@cc iut ac ir Dr Mehdi Ranjbar Ranjbar@cc iut ac irAbstractElectrochromic EC property is the continuous reversible changing of optical transmission absorption orreflection of materials by applying electric voltage Tungsten oxide is one of the most applicable ECmaterials due to its high response velocity appropriate coloring performance and good chemical stabilitynear electrolyte solutions EC devices are extensively used in smart windows rear view mirrors inautomobile digital displays photo electrochemical cells etc These devices play an important role incontrolling and saving energy The aim of this study is to enhance the efficiency of WO3 based EC devices The crystal structure oftungsten oxide is one of the effective factors in EC performance of WO3 thin films WO3 crystals transformstructurally under heat treatment Therefore first the effect of heat treatment on EC characteristic of WO 3thin films was investigated It was observed that heat treatment leads to the reduction of ionic speciespenetration into the structure by compacting the crystal structure of WO 3 and hence cuases a decrease in ECefficiency of films Since electrochemical reactions have significant influence on EC efficiency theselection of a suitable electrolyte solution in the presence of an ion storage material is of interest Phosphoric acid electrolyte solution is an appropriate ion conductor because of its small light H ions Moreover Palladium Pd is a well known hydrogen storage metal with high speed of storage So theeffect of Pd on H absorption rate in WO3 thin films and EC response was explored Our findings show thatalthough Pd is capable to store electric energy by decreasing the reduction energy of tungsten oxide it canact as a barrier against H penetration into WO3 structure Furthermore the effect of aging onelectrochemical characteristics of pure and Pd doped samples was tested Our results indicate that Pdincreases the chemical stability of WO3 thin films as well as EC durability To prepare pure and Pd doped WO3 thin films the obtained tungstic acid via sol gel route was doped withPd in different molar ratios The final sol was deposited on transparent conducting glass substrates FTO by dip coating method The characterization of samples was achieved using cyclic voltammetry CV technique X ray diffraction XRD atomic force microscope AFM field emission scanning electronmicroscope FE SEM Fourier transform infrared spectroscopy FTIR UV Vis spectroscopy and adesigned setup for recording optical transmittance It has been demonstrated that the presence of pd in theWO3 sol in the vicinity of phosphoric acid won t increase the EC efficiency of films generally Keywords Electrochromic tungsten oxide sol gel dip coating palladium

حاجيان، شيرين

بررسي خواص الكتروكروميكي لايه هاي نازك تنگستن اكسيد (WO3) و تنگستن اكسيد آلايش يافته با پالاديم (WO3-Pd)

سل - ژل , لايه نشاني غوطه وري