Fabrication And Performance Test Of Electrochromic Devices

Electrochromic?EC?devices possess the advantages of low operating voltage,multi stable state,static non power consumption,low power consumption for color change,continuous adjustable transmittance/reflectance,long lifetime,fast response time,and low manufacturing cost.As the result,the electrochromic devices have a great application potential in smart windows.The electrochromic devices can be divided into organic electrochromic devices and inorganic electrochromic devices,according to the electrochromic material.Examples of organic electrochromic materials are viologen,conjugated polymers,etc.,while the inorganic electrochromic material is predominantly tungsten oxide.In the thesis,both inorganic and organic electrochromic devices are studied.Using WO₃ as the inorganic electrochromic material,the film quality of the WO₃ layer deposited under different conditions is analyzed by SEM.After the assembly of the inorganic electrochromic device,the device performance is investigated,such as the optical modulation amplitude,and the response time.In addition,the Ag-WO₃ composite film is used as the electrochromic layer,and the device performance is compared that of the device with WO₃ electrochromic layer.Meanwhile,the device stability of the organic electrochromic devices is studied by varying the external temperature and the irradiated light intensity.For WO₃ devices,the device will switch between blue state and transparent date under DC voltages with different polarities.The film quality of the magnetron sputtered WO₃ film depends on the argon-oxygen partial pressure ratio,leading to different device performance.The optical modulation amplitude and the response time of the device increase first,and then decrease with the increase of the argon-oxygen partial pressure ratio.The shortest response time isobtained by the argon-oxygen partial pressure ratio of 50:50.For Ag-WO₃ devices,the Ag-WO₃ composite film is deposited by electron beam evaporation and magnetron sputtering.Comparted to WO₃ devices,the response time is significantly shorter,while the optical modulation amplitude becomes worse due to the difference of transmittance in the colored state and the transparent state.For organic electrochromic devices,the conjugated polymer becomes dark blue under positive driving voltage,and light blue under negative driving voltage.Both states return to a normal blue state after power off.Under a fixed light irradiation,the decay rate of the device accelerates with the increase of the device temperature.Under a fixed device temperature,the decay rate of the device accelerates with the increase of the irradiated light intensity.