Fabrication Of Paper-based Silver Nanowire Film Heaters And Thermochromic Application

Paper-based thermochromic device is a kind of convenient,low-cost information display device,among which the paper-based heating substrate with good electrical conductivity is one of the most important research.Silver nanowires are widely concerned because of their high light transmittance,low surface resistance and excellent flexibility.However,it is difficult to fabricate uniform paper-based silver nanowires films due to their characteristics of porous water absorption.In this paper,a large area of paper-based heater is obtained by means of superposition and spraying,with the non-uniformity as low as 4.95%and the resistance continuously adjustable from 1 Ω.sq-1 to 100 Ω.sq-1.Subsequently,different thermochromic inks are screened on paper,and a variety of color changes can be realized by adjusting the temperature of the heater.The main achievements of this paper are as follows:(1)The effects of structural parameters of silver nanowires on the photoelectric properties of silver nanowire transparent conductive films were studiedSeven groups of silver nanowires with different sizes and specifications were synthesized,and a series of transparent conductive films of silver nanowires with different electrical resistance values were prepared.The effects of different structure parameters of silver nanowires on the photoelectric properties of transparent conductive thin films were studied.The results show that under the same electrical parameters,the larger the diameter of silver nanowires,the greater the haze,and the larger the length of silver nanowires,the higher the transmittance in the size range(diameter 20 nm-120 nm,length-diameter ratio less than 1500).Finally,a transparent conductive silver nanowire thin film with sheet resistance less than 75 Ω.sq-1 and highly uniform was fabricated,its optical index is more than 80%at 550 nm wavelength,and its haze is greatly adjustable between 1.2%and 23%.According to the requirements of the heater,the silver nanowires with medium diameter and large aspect ratio were determined to be the suitable raw materials for fabricating paper based thermochromic devices.(2)Determine the influence distribution factors and continuous regulation rules of surface resistance in the process of preparing silver nanowire films by spraying methodFor the silver nanowire synthesized by polyol method,the stable ink suitable for spraying method was obtained by adjusting the composition parameters of the nanowire ink.We present a model based on the principle of superposition spraying for the preparation of transparent conductive films.In the experiment,the influence of three different stacking methods on the film resistance uniformity was compared,and the parameters such as air pressure,ink surface tension and viscosity,and substrate pretreatment method were optimized.The experimental results show that the film size can reach 6 cm × 6 cm,and the resistance inhomogeneity is less than 10%.By adjusting the solid content of silver nanowires in the ink,the sheet resistance of the film can be continuously adjusted in the range of 1 Ω.sq-1～100 Ω.sq-1 to meet the needs of different devices.(3)Clarify the thermal response rule of the paper-based silver nanowire heaterOn paper silver nanowires film with high evenness was prepared by spray coating,late through the surface of colloidal silica coating and the preparation of electrode,paper-based silver nanowires heater can be long-term preservation.Through the thermal test,we can control the thermal response performance of the heater by adjusting the voltage,resistance and heat exchange coefficient of the heater.(4)The multi-functional discoloration effect of silver nanowire paper based thermochromic device is demonstratedThe thermochromic pigment is coated on the surface of the paper-based heater by screen printing,and the change of the color of the surface pattern is controlled by the change of temperature,so that the rapid and reversible switch of different patterns is realized,and a new attempt is made for the exploration of the new paper-based display.