| Electrochromic materials can undergo reversible changes in optical properties under the effect of an applied voltage,and have the advantages of dimming and low energy consumption.In today's increasing energy shortage,smart windows based on electrochromic materials can effectively reduce building energy consumption and show a good application prospect in the field of construction.The unique pore structure of Metal-Organic Frameworks(MOFs)materials can provide favorable conditions for the entry and exit of ions and electrons in the process of electrochromism,which has attracted the attention of researchers in recent years.In this paper,manganese-based metal organic framework(Mn-MOF)materials were used as research objects.Two kinds of Mn-MOF films were prepared on the surface of transparent conductive glass by hydrothermal method and electrochemical method,and the electrochromic properties were tested.Prussian blue(PB)film was prepared on the transparent conductive glass with Mn-MOF film grown by electrochemical method to obtain Mn-MOF/PB composite film,and its electrochromic properties were studied.The main research results of this paper are as follows:(1)Mn-ptcda films were prepared by hydrothermal reaction on the surface of fluorine-doped tin oxide(FTO)transparent conductive glass,with the basic mixture of manganese acetate tetrahydrate and perylene-3,4,9,10-tetracarboxylic dianhydride(ptcda)as the precursors.By changing the temperature of the hydrothermal reaction and the concentration of the precursor solution,the optimal conditions for Mn-ptcda film formation were obtained.When the precursor solution was hydrothermally reacted at 140?,the homogeneity and electrochemical properties of the films were better.Mn-ptcda films were prepared by hydrothermal reaction at 140?for 24 hours with a mixture of 0.036 mol·L-1aqueous solution of manganese acetate and 0.032 mol·L-1 basic solution of ptcda as precursors.The obtained Mn-ptcda film exhibited good electrochromic properties:its optical modulation amplitude reached its maximum at 428 nm,which was 25.2%.In the precursor solution,0.0324 mol·L-1 manganese acetate and 0.0036 mol·L-1 cobalt acetate were mixed uniformly and dissolved in water,mixed with ptcda alkaline solution as a precursor solution for hydrothermal.The doping of cobalt ions is achieved,and a cobalt-manganese metal organic framework film(Co-Mn-ptcda)was obtained on the surface of FTO glass.Its electrochromic property test results showed that the cobalt doping had a certain negative effect on the film formation effect,and affected the original electrochromic property of the Mn-ptcda film.(2)Using 0.1 mol·L-1 manganese acetate solution as the electrolyte,a Mn2O3 film was electrodeposited on the surface of indium tin oxide(ITO)transparent conductive glass by chronopotentiometry.Subsequently,the prepared film was sequentially immersed in 20 m L of2,5-Dihydroxyterephthalic acid(DHTP)in N,N-dimethylformamide(DMF)solution,20 m L of manganese acetate in DMF solution and 20 m L of DHTP in DMF solution in order to obtain Mn-DHTP film with guest molecule DHTP.The Mn-DHTP film exhibited a color change between blue and light gray,and the light modulation amplitude reached a maximum at 800 nm,which was 44.6%.It was assembled with ITO transparent conductive glass to form an electrochromic device.The optical modulation amplitude reaches the maximum at 796 nm,which was 15.9%.The coloring response time of the device was 152 s,and the fading response time was 193 s.(3)Electrodeposition method was used to electrodeposit PB film on FTO conductive glass with Mn-ptcda film grown to obtain Mn-ptcda/PB composite film.The PB film was deposited uniformly on the surface of the Mn-ptcda particles,and the bondingwas relatively strong.The Mn-ptcda/PB composite film exhibited good electrochromic properties,and its optical modulation amplitude reached the maximum at 730 nm,which was 41.2%.The composite film and FTO transparent conductive glass were assembled into a device,and its optical modulation amplitude reached the maximum at 792 nm,which was 12.6%;its fading response time was about 21.5 s,and the coloring response time was about 50.6 s. |
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