Variable Infrared Emittance Devices Based On Reversible Silver Electrodeposition

With the rapid development of optoelectronic technologies,current reconnaissance methods are able to precisely detect and attack military targets.Infrared imaging technology is widely used in military fields due to its good concealment,long night vision distance and free from sunlight,which poses a great threat to military equipment and personnel.Therefore,dynamic control of infrared radiation characteristics of various military targets has become an inevitable trend in the next generation camouflage technology.To achieve this goal,the radiant heat emitted from an object should be precisely controlled to match the background.In this thesis,we started from the reversible metal electrodeposition,selected nanoscopic metal films and graphene films as the top electrodes of the electrodeposition system,studied the infrared modulation potential of these two electrode materials in reversible silver（Ag）electrodeposition devices,achieved substantial emittance modulation range in these devices,and finally explored the multifunctionlization potentials of the nanoscopic metal films based devices.The main content is as follows:（1）We used nanoscopic platinum（Pt）film as the top electrodes.The infrared absorption and transmission of the nanoscopic Pt films could be converted to infrared reflection,so we realized substantial emittance modulation range in the infrared window bands（3-5μm and 7.5-13μm）.Firstly,we prepared the nanoscopic Pt films of different thickness on Ba F₂ substrate by electron beam evaporation process,and analyzed the electrical conductivity and optical properties of the Pt films to verify the potential modulation range of the Pt electrodes in reversible Ag electrodeposition system.Secondly,the Pt/Ba F₂ substrates were assembled into the devices,and the influence of Pt thickness and deposition voltage on the dynamic infrared performance was studied by means of infrared camera and infrared spectrometer.The experimental results show that the device has large infrared emittance modulation range,uniform variation and high modulation consistency in the infrared window band.Finally,through cycling tests and radiation cooling experiments,the cycling limit of the devices were studied,as well as their advantage of using non-infrared detection window band for extra radiative cooling.（2）Through layer-by-layer wet transfer method,we effectively transferred multilayer graphene films onto Si O₂/Si,Ba F₂,and PP substrates,and achieved graphene-based variable infrared emittance devices.Firstly,the effectiveness of graphene transfer process and the feasibility of metal deposition were verified on Si O₂/Si substrate.And the effect of deposited metals on the infrared reflectance of Si O₂/Si substrate was also studied.Secondly,we investigated the transfer process of graphene on the infrared transparent substrates such as barium fluoride（Ba F₂）and polypropylene（PP）,and studied the surface treatments and the number of graphene layers on the infrared transparency and electrical conductivity of the substrates.Finally,the dynamic infrared performance of graphene-based devices was studied by infrared camera,and the dynamic infrared regulation potential of graphene under this system was preliminarily verified.（3）By comparing the dynamic infrared characteristics of the two electrodes,the nanoscopic Pt films with better performance were selected as the top electrodes for explorating device multifunction.First,the nanoscopic Pt film was patterned by mask,and a 3×3 array device was prepared,showing the multiplexing potential of the Pt-based devices.Second,by adding conductive grid to nanoscopic Pt film,the deposition voltage uniformity could be improved,demonstrating that the effective modulation area of the device can be easily enlarged.Third,by replacing the substrates with rough Ba F₂substrates or flexible PP films,the variable infrared emittance devices could achieve diffuse infrared reflection mode or flexibility.Fourth,by adding Cr₂O₃ interference layers,variable infrared emittance devices with visible compatibility could be prepared.