Study On Preparation And Electrochromic Performance Of Polyaniline-based Composite Materials

In recent years,electrochromic materials have great potential in energy conservation and environmental protection because they can effectively regulate the transmittance of sunlight.Electrochromism refers to the phenomenon that a low voltage（<3V）is applied to a material,causing it to undergo a redox reaction,resulting in a change in optical properties such as transmittance,absorbance and reflectance.Electrochromic materials are widely used in building glass,low-energy displays,wearable clothing,mobile phone cases and aircraft portholes.Polyaniline（PANI）,as one of the classical conductive polymer electrochromic materials,has many advantages such as rich color variation,low redox potential,low cost and simple preparation method.However,its response time,cycle stability and optical modulation range are still not ideal,which limits its development in practical life.In order to solve the above problems,two kinds of polyaniline-based composite electrochromic materials were designed and prepared in this paper.The crystal structure,surface morphology,elemental composition,electrochemical performance and electrochromic performance of the films were analyzed by XRD,SEM,EDS,electrochemical testing and spectroscopic testing.Specific research contents are as follows:（1）A series of WO₃/PANI composite films were obtained by compounding tungsten trioxide（WO₃）films with PANI films under different deposition conditions by a two-step electrochemical deposition method.It was found that WO₃ films prepared at a deposition voltage of-0.5 V and a deposition time of 700 s were compounded with PANI films prepared at a deposition voltage of 1.5 V and a deposition time of 600 s to obtain the best electrochromic performance of WO₃/PANI composite films.Compared with WO₃ and PANI films prepared under the same conditions,the WO₃/PANI composite film has a larger optical modulation range（ΔT=51.8%）,shorter response time（0.8 s/1.9 s for coloring response time/fading response time,respectively）and higher coloring efficiency(CE=26.42 cm²·C^-1).In addition,the composite film still maintains good stability after 300 cycles,and its color changes from blue,light yellow,green to light blue.The improvement of electrochemical and electrochromic properties of WO₃/PANI composite films is mainly attributed to the formation of the donor-acceptor（D-A）structure between WO₃ and PANI.（2）A series of Au/PANI composite films were obtained by combining the electrostatic adsorption self-assembly method and electrochemical deposition method to compound the gold nanoparticle films with PANI films at different soaking times.It was found that the gold nanoparticle films prepared under the conditions of soaking time of 1.5 h were compounded with PANI films under the conditions of deposition voltage of 1.2 V and deposition time of 120s to obtain Au/PANI composite films with the best performance.Compared with PANI films prepared under the same conditions,the Au/PANI composite film has a wider optical modulation range（ΔT=38.4%）,shorter response time（coloring response time/fading response time of 0.9 s/0.6 s）,and higher coloring efficiency(CE=33.56 cm²·C^-1).The high conductivity of gold nanoparticles may be the main reason for the improvement of electrochemical performance and electrochromic properties of Au/PANI composite films.