Preparation And Electronic Applications Of Transparent All-cellulose Films With High Haze

Transparent films made from cellulose materials have the advantages of low cost,biodegradability,light weight and foldability,regarded as the ideal and sustainable substrate for flexible electronic devices.In addition to supporting the device mechanically,the transparent cellulose film can also be designed as the function layer of the device to improve the performance.In this paper,a highly hazy and transparent all-cellulose based on cellulose fibers and sodium carboxymethyl cellulose（CMC-Na）was rapidly prepared by a combination of papermaking method and impregnation.The main research contents as follows:（1）The effects of fiber beating,base weight of regular paper and fiber species on optical and mechanical properties of transparent all-cellulose films were investigated.（2）The water-resistant modification of the all-cellulose film was carried out and the mechanism was explored.（3）Study on device fabrication based on transparent all-cellulose films with high haze.The main conclusions are as follows:1.We reported a facile and scalable impregnation to fabricate transparent all-cellulose film with high haze.The all-cellulose film exhibited a maximum light transmittance of 90%and superior tensile strength as the mass ratio of CMC-Na（molecular weight:700000 Da）to softwood fiber is 7:3,the resulting film combined a high optical haze（up to 82%at 550 nm）with superior mechanical properties(140 MPa tensile strength,8.5 MJ m^-3 toughness,and over3000 folding times).Moreover,the all-cellulose film demonstrated an ultra-smooth surface（Rq of 0.9 nm over a scanning area of 2*2μm²）and improved flame retardant performance（with an onset decomposition temperature of 254°C and LOI of 30%）.2.The mainly influence factors of mechanical and optical properties of all-cellulose films were studied.With the increase of beating degree of cellulose fibers,the transmittance of prepared all-cellulose films remained unchanged,the transmission haze decreased,the tensile strength increased,and the folding endurance increased firstly after declining;Increasing the base weight of regular for impregnation had little effect on the high transmittance and tensile strength of the all-cellulose films,which could increase the optical haze and decrease the folding endurance;The fiber species did not affect the transparency of all-cellulose films,but the larger the length and width of the fiber,and the greater the haze,tensile strength and folding strength of the all-cellulose film.3.We proposed a facile water resistant modification method combining protonation process with a desalination.The all-cellulose film showed a negligible deterioration in optical and mechanical properties compared with the untreated all-cellulose film.The all-cellulose film presented an enhanced water resistance,with a water contact angle of 72°,a change in thickness up to 25%and a water absorption ratio of 60%after soaking it in water for 6 h.4.We aslo presented the use of transparent all-cellulose film with high optical haze for electronic devices.The electrical conductivity of inkjet-printed silver nanoparticle line deposited on all-cellulose film was investigated,after soaking in water for a period of time,the resistance of conductive line on water resistant film increased from 53Ωto 88Ω;EL device was fabricated on transparent all-cellulose film,which exhibited certain luminescent property;The all-cellulose film was also used as function layer for perovskite solar cell,PCE of solar cell increased by 5.4%.