Study Of Compatible Type Infrared Electrochromic Device Based On Polyaniline Conducting Polymer

With the development of reconnaissance, the traditional camouflage device causes the exposure of the target easily, due to the fixed infrared characteristic signal, which would not match the target any more, when the external environmental condition changes. Aim at the issue, a visible, near- infrared compatible type of infrared electrochromic device based on polyaniline(PANI) was designed in this paper, the emissivity of which would change with the change of the external environmental condition, under the action of voltage. The device could meet the camouflage requirement of the southern woodland, gave consideration to both the adjustable emissivity of the device and the compatible of the camouflage performance under visible, near-infrared wave band of the external environmental condition. The main contents and conclusion are as follows:The requirements of the infrared electrochromic device under visible, near- infrared and thermal infrared wave band were analyzed. According to the collected infrared characteristics in the same environment at different times and in the different environment at the same time, the change rules of the infrared characteristics with environment and time were obtained. The main performance parameters of the device were clearly, and the intelligent camouflage basic concepts, which included the priority research on green colour system, compatibility with the near-infrared wave band and the adjustable infrared emissivity, were put forward at the same time. The design plan based on PANI was confirmed which using the band gap effect of photonic crystal to realize the compatible camouflage of the device in near- infrared band.The PANI working electrodes of the infrared electrochromic device were prepared on gold plating porous membranes by electrochemical polymerization and the influences of voltage, current density and columbic density of polymerization on the morphology, structure and initial emissivity of PANI electrodes had been studied. The study had shown that when the PANI electrodes were prepared by galvanostatic method, the initial emissivity of the electrode increased with the increase of the polymeric columbic density, while the doping degree kept nearly unchanged. When the PANI electrodes were prepared by potentiostatic method, with the increase of the polymeric columbic density, both the initial emissivity and the doping degree increased. The galvanostatic method was better at the controlling of the thickness of PANI layer on the working electrode, while the potentiostatic method was better at the controlling of the initial emissivity of the working electrode.The influence of the preparation conditions of each component on the performance of the infrared electrochromic device had been studied, and the electrochromic mechanism model of the device was estimated and verified. The conclusions are as follows: frist, the optimal thickness of the gold layer on the porous membrane is 160~200 nm, and the pore size of the porous membrane is less than 5 μm. Second, with the increase of the polymeric columbic density, the dynamic range of the infrared emissivity of the device increased first, and then decreased. Third, the doping of PANI would improve its water-solubility. After doping, the PANI working electrode would be prepared by spray coating, but the dynamic range of emissivity decreased. Fourth, about the 8~12 μm wave band device, when the initial emissivity is low(about 0.6), the control scope of the emissivity is 0.3~0.6, the maximal dynamic range is 0.3. When the initial emissivity is medium(about 0.8), the control scope of the emissivity is 0.33~0.8, the maximal dynamic range is 0.47. When the initial emissivity is high(about 0.9), the control scope of the emissivity is 0.37~0.9, the maximal dynamic range is 0.53. Fifth, the emissivity of the device varied at the different voltage, due to the different PANI absorption at infrared wave band, which is related to transmission mode mechanism.The compatibility in the near- infrared wave band of the device was realized by the band gap effect of photonic crystal. The theoretical calculation and preparation of PANI inverse opal photonic crystal and one-dimensional photonic crystals based on polyethylene were carried out. The studies showed that, first, according to the theoretical calculation of the structure of inverse PANI opal photonic crystal, when the diameter of Si O2 is 500 nm, the reflective peak of the PANI’s photonic band gap is at 700 nm, which would meet the requirements of the high reflecting property at near-infrared band. Second, a series of the PANI inverse opal photonic crystal were prepared successfully. When the pore diameter is 800 nm, the photonic band gap peak of PANI inverse opal was obvious at 1370 nm. Third, according to the theoretical calculation of the structure of the one-dimensional photonic crystals, the optimal structure to obtain high reflecting property at near- infrared band is the thickness of monocyclic layer of Si/Si O2 is 250 nm, in which the thick ness of Si is 175 nm, and the thickness of Si O2 is 75 nm, and the repetition period is 2. Fouth, the one-dimensional photonic crystal was prepared successfully, which would increase the reflectivity of the device at the near-infrared wave band, and had little influence on the infrared electrochromic performance.