Fabrication And Properties Of Self-powered Electrochromic Devices Based On Prussian Blue Nanomaterials

Self-powered electrochromic devices(ECDs)without an external power supply have been attracting extensive attention owing to their great potential in diverse electronic areas.However,conventional self-powered ECDs generally suffer from a complicated configuration,inflexibility,and poor color switching properties,which limit their applications.Here,we develop a flexible self-powered quasi-solid-state ECD with a simplified bilayer film configuration based on a cathodic Prussian blue(PB)film and an ionic hydrogel film,in which the ionic hydrogel film serves as the quasi-solid electrolyte and ion storage layer and an aluminum wire acts as both conductive circuit and anode material.Owing to the elaborate bilayer structure and unique ionic hydrogel film,the self-powered ECD exhibits fast color switching speed,high reversibility and tunable coloration rate on demand.Impressively,the ECD possesses the capability of"reviving" its color switching properties after repeated cycling,which significantly extends its lifetime.We demonstrated the practical applications of the self-powered ECDs in differentiated information encryption and decryption.These findings may open a new way to design self-powered ECDs with new functions and thus explore new applications.The specific research content is as follows:(1)Preparation of self-powered ECDIn this thesis,we demonstrate a new kind of self-powered quasi-solid-state ECD based on a simplified bilayer film configuration.The electrochromic film is PB cathodic film which electrodeposited on indium tin oxide/polyethylene terephthalate(ITO/PET)substrate.The polyacrylamide/lithium chloride(PAM/LiCl)gel film is developed as both quasi-solid-state electrolyte and ion storage,and it's prepared through polymerization of acrylamide(AM)monomer containing aqueous LiCl using(NH4)2S2O8 and N,N'-methylenebis(acrylamide)as initiator and cross-linker,respectively.The self-powered ECD with bilayer film configuration is simply realized through the integration of a PB cathodic EC film based on(ITO/PET)substrate with an ionic PAM/LiCl hydrogel film.The color-switching processes of the device is achieved by connecting or disconnecting the Al wire between the bilayer film configuration.The self-powered ECD has high transparency,flexibility and ionic conductivity,enabling the practicability of flexible self-powered ECDs.(2)Color switching performance of self-powered ECDThe self-powered ECD has excellent color switching performance.Fast color bleaching from blue PB to colorless Prussian white(PW)only needs 6.8 s.On the contrary,the coloration process needs 8.0 min.The corresponding response time,Tb and Tc of the self-powered ECD is 5.0 s,and 5.0 min,respectively.The ECD has excellent cycle performance,it can run over 50 times without significantly decrease.In addition,when the color switching performance of the ECD declines after repeated cycles,self-powered ECD exhibits unprecedented "revived" color switching properties by simply reactivating the PAM/LiCl gel film with solution,thereby greatly extending their switching performance(Up to 100 cycles).(3)Application of ECD in information encryption/decryptionIn order to improve the practicability of self-powered ECD,we use laser etching technology and electrodeposition of PB to prepare encrypted ECD.The decryption information could be selectively controlled by simply changing the conduction region,showing great promising for applications in security information and high-level anticounterfeiting.In addition,the PAM/LiCl gel film with different amount of(NH4)2S2O8 has the ability to tune the coloration rate on demand,we further integrate the encrypted patterns with two PAM/LiCl gel films.This self-powered ECD with encrypted information and tunable coloration time on demand exhibits decrypted information with differentiated color contrast changing with time.Therefore,the readers cannot recognize which state is the true information in the self-powered ECD without advance notice,which greatly enhances the practical security application for information encryption,valuable product authenticity and anti-counterfeiting.