Synthesis and Characterization of Thermochromic VO2 Nano Material by Chemical Bath Deposition Method for Energy Efficient Glass Windows

Abstract

Thermochromic vanadium dioxide (VO2) is successfully deposited on microscope glass substrate by chemical bath deposition method for the first time using potassium hydroxide (KOH), Triethanolamine (TEA) as complexing agents and Polyvinylpyrrolidone (PVP K-30), as a surface modifying agent. The common synthesis methods for thermochromic VO2, which are chemical vapour deposition and physical vapour deposition, does not make this material commercialized due to scalability and cost effectiveness problems. The chemical bath deposition (CBD) method applied in this project includes, selection and optimization of appropriate chemicals for the synthesis by powder preparation using three trials then annealed in nitrogen gas at 570 ºC. Based on the result found on the three trials the one, which shows better formation of pure phase VO2 is further used for the thin film deposition. During the thin film deposition process, the microscope glass is pre coated with Polyvinylpyrrolidone to assist the surface modification and selectively attract VO2 phases towards the substrate so that better adhesion with high purity VO2 thin film is formed. The thin film material are prepared with different conditions, by varying deposition time, in such way that a 15 minutes, 30 minutes and 80 minute deposited thin film and annealed at 450 C, 500 C and 570 C in nitrogen gas. Differential thermo gravimetric (DTG). The Nano martial produced shows thermochromic transition behavior at average of 69 ºC based on Differential scanning calorimetry (DSC) studies. UV-VIS spectrophotometer analysis for 15 minutes and 30 minutes deposited thin film shows shielding of near infrared region (NIR) wavelength 3.7 % and 5.5 % respectively. Based on the XRD studies of the film two dominant peaks at 27.6 degree and 39.5 degree are observed with (011) and (020) planes of VO2 respectively. In addition to this, crystallinity increases with annealing temperature as the FWHM shows 0.00380 rad and 0.00320 rad for 500 C and 570 C annealing temperature respectively. Scanning electron microscope (SEM) analysis done for 30 minute deposited thin film shows increase in grain size and decrease in grain boundary with increase in annealing temperature. Based on the results of analysis, thin film material prepared using chemical bath deposition (CBD) have shown promising properties for future application in smart window application to regulate indoor temperature without applying external energy.Thermochromic Vanadium Dioxide (Vo2) Is Successfully Deposited On Microscope Glass Substrate By Chemical Bath Deposition Method For The First Time Using Potassium Hydroxide (Koh), Triethanolamine (Tea) As Complexing Agents And Polyvinylpyrrolidone (Pvp K-30), As A Surface Modifying Agent. The Common Synthesis Methods For Thermochromic Vo2, Which Are Chemical Vapour Deposition And Physical Vapour Deposition, Does Not Make This Material Commercialized Due To Scalability And Cost Effectiveness Problems. The Chemical Bath Deposition (Cbd) MethodApplied In This Project Includes, Selection And Optimization Of Appropriate Chemicals For The Synthesis By Powder Preparation Using Three Trials Then Annealed In Nitrogen Gas At 570 ??C. Based On The Result Found On The Three Trials The One, Which Shows Better Formation Of Pure Phase Vo2 Is Further Used For The Thin Film Deposition. During The Thin Film Deposition Process, The Microscope Glass Is Pre Coated With Polyvinylpyrrolidone To Assist The Surface Modification And Selectively Attract Vo2 Phases Towards The Substrate So That Better Adhesion With High Purity Vo2 Thin Film Is Formed. The Thin Film Material Are Prepared With Different Conditions, By Varying Deposition Time, In Such Way That A 15 Minutes, 30 Minutes And 80 Minute Deposited Thin Film And Annealed At 450???C, 500 ???C And 570 ???C In Nitrogen Gas. Differential Thermo Gravimetric (Dtg). The Nano Martial Produced Shows Thermochromic Transition Behavior At Average Of 69 ??C Based On Differential Scanning Calorimetry (Dsc) Studies. Uv-Vis Spectrophotometer Analysis For 15 Minutes And 30 Minutes Deposited Thin Film Shows Shielding Of Near Infrared Region (Nir) Wavelength 3.7 % And 5.5 % Respectively. Based On The Xrd Studies Of The Film Two Dominant Peaks At 27.6 Degree And 39.5 Degree Are Observed With (011) And (020) Planes Of Vo2 Respectively. In Addition To This, Crystallinity Increases With Annealing Temperature As The Fwhm Shows 0.00380 Rad And 0.00320Rad For 500 ???C And 570 ???C Annealing Temperature Respectively. Scanning Electron Microscope (Sem) Analysis Done For 30 Minute Deposited Thin Film Shows Increase In Grain Size And DecreaseIn Grain Boundary With Increase In Annealing Temperature. Based On The Results Of Analysis, Thin Film Material Prepared Using Chemical Bath Deposition (Cbd) Have Shown Promising Properties For Future Application In Smart Window Application To Regulate Indoor Temperature Without Applying External Energy.