Research On Preparation And Applications Of Flexible/stretchable ZnS:Cu Electroluminescent Device

The emergence of wearable electronic devices has brought tremendous changes to human life style.Flexible/stretchable electroluminescent devices are indispensable components of wearable integrated device systems in the future,which have great development prospects.At present,electronic devices are gradually showing a trend of miniaturization,low power consumption,and versatility.The design of flexible/stretchable electroluminescent devices should take into account luminescent materials,electrode materials,functional materials,device structure and mobile energy supply.Triboelectric nano-generator?TENG?is a kind of technology device which converts mechanical energy into electrical energy.The self-powered system based on nano-generator can collect different forms of low-frequency mechanical energy in the environment,which has broad application prospects in the fields of self-powered micro-nano system of mobile electronic products and the new generation of Internet of Things.A stretchable ZnS:Cu alternating-current electroluminescent?ACEL?device is proposed based on the flexible/stretchable luminescent system and the self-powered system of TENG in this work.Firstly,the work choose ZnS:Cu as luminescent material,single-walled carbon nanotubes?SWCNTs?films as stretchable transparent electrodes and fabricate stretchable ACEL device.And the work choose fluorinated ethylene propylene?FEP?,aluminum?Al?foil etc.to fabricate contact-separated TENG.Secondly,the morphology,structure and relevant properties of the prepared materials and devices were characterized.Thirdly,an integrated system of stretchable transparent ACEL device and contact-separated TENG was designed and constructed.Then,the electroluminescence?EL?performance of the stretchable transparent ACEL device in the integrated system under the original state and tensile state were investigated separately.Finally,the effects of stress and electric field double stimulation on the luminescent properties of ACEL device were investigated.The main results are as follows:?1?ZnS:Cu phosphors with uniform particle size were prepared by high temperature solid-state method.The surface morphology,crystal structure,sample composition and photoluminescence?PL?spectra were analyzed by field emission scanning electron microscopy?FE-SEM?,X-ray powder diffraction?XRD?,energy dispersive X-ray spectroscopy?EDS?and F-7000 fluorescence spectrometer.The prepared samples were proved to be ZnS:Cu phosphors with good luminescent properties.PreparationofstretchableelectrodesandZnS:Cu/PDMS electroluminescent layer?filling ratio 9.1%,thickness 50?m?using ZnS:Cu phosphors,SWCNTs,polydimethylsiloxane?PDMS?,etc.A sandwich-structured stretchable electroluminescent device was fabricated using ZnS:Cu/PDMS electroluminescent layer and stretchable electrodes.The transmittance of the ACEL device was 76%in the visible-near infrared region.?2?The work makes contact-separated TENG,using FEP,aluminum foil,copper?Cu?,and polyimide film?Kapton?.The TENG has an external resistance of 100 M?for an optimum output power of 27?W,matching the impedance of a stretchable ACEL device.A self-powered integrated system of stretchable ACEL device and contact-separated TENG was constructed.The stretchable ACEL device in this system can keep stable and continuous operation in up to 100%quasi-static and dynamic deformation states.?3?The work tests the luminescence properties of ACEL device under double stimulation of stress and electric field,while maintaining the same voltage.It can be found that the stress can influence the luminescent intensity of the ACEL device as follows.The relative intensity?I-I₀?I₀increases rapidly with the increase of pressure in the pressure range of 0 Pa-200 Pa.And the relative intensity?I-I₀?I₀slowly increases with the increasing pressure,if the pressure ranges from 200 Pa to1200 Pa.The relative luminescent intensity remains substantially unchanged when pressure exceeds 1200 Pa.