Doped-PEO Tungsten Oxide Thin Film

With the development of economy and people’s living standards, more and more people feel the importance of adjusting natural environment artificially. After electrochromism was first forwarded by Platt, electrochromic phenomenon has drawed wide attention. Tungsten oxide thin film is studied as an important electrochromic material, it is reversible in transiting from transparent to blue state, therefore is widely used in preparing various electrochromic devices and smart window.

Inorganic-organic nanocomposite material is becoming an energetic research field which attracts many researchers. It combines excellent property of inorganic, organic and nano materials which would become an important new multifunction material, has good mechanical, optical, electrical and magnetic properties. PEO (polyethylene oxide) can accelerate conductivity of ion and electron. Reaction time of tungsten oxide thin film prepared by sol-gel method is faster than by sputtering method. Doping certain amount of PEO would improve response time and discoloration property of thin film.

Electrochemical property

Below is the cyclic voltammetry curves of sample, scanning rate is 50 mV /s, forward scanning is from + 1. 5 V. Sample is thermal treated under 200℃ by protection of N2. From which we can see the input and output currency density of Li+ is 1. 25 mA /cm2 and 0. 4 mA /cm2, the cycle reversibility is better, and coloring and fading speed is faster.

Visible light transmittance

Below is the transmittance curves of sample. a is before discoloring, b is after discoloring. From the chart we can see the rate of transmittance can reach 35%, so it can be used to producing electrochromic device and smart window.

It turns out that doping a certain amount of PEO in tungsten oxide thin film will accerate the conductivity of ion and electron in thin film, also will improve the reaction time and discoloration property of thin film.