Effect Of Electron-transporting Layer On The Perforamnce Of Organic Bifunctional Device With Electroluminscence And Detection Properties

The bifunctional device with the properties of organic light-emitting device and organic photodetector?OLED-OPD?can achieve light emission and photo detection in a specific wavelength range simuteneusoly.More and more researchers have paid close attention to the research of bifunctional device.At present,the research work of bifunctional devices is mainly focused on the development of novel active layer?AL?or exciton adjusting layer?EAL?materials.However,there is still research required to focus on the effect of electron-transporting materials?ETMs?on the properties of bifunctional device.In this paper,we used a thermally activated delayed fluorescence?TADF?material as the AL material to fabricate bifunctional device with ultraviolet?UV?detection and electroluminescent?EL?.And we systematically studied the effects of ETMs on UV detection and EL properties.The specific research content is as follows:?1?A series of organic OLED-OPD bifunctional devices were fabricated based on different ETMs.Five kinds of N-type materials,including 3TPYMB,Bphen,BCP,TmPyPB and TPBi,were used as ETMs,respectively.The OLED-OPD bifunctional devices with TADF material as active layer material were fabricated,and the effect of different ETMs on the detection performance of the device was first analyzed.By comparison,it can be found that the level and carrier mobility of electron transport material affect the photocurrent and dark current,and then affect the detectivity of the device.The variety of detectivity was from 10⁹ to 10¹¹ Jones with two orders of magnitude.?2?Comparing with the EL properties of OLED-OPD bifunctional devices,we studied the difference of the EL properties of the devices under different energy levels and electron mobility.By analyzing the current density-voltage-luminance curve,the changing trend of the turn-on voltage and the relationship between the current efficiency and voltage,the effect of the energy level and electron mobility of the electron-transporting layer on the luminous performance of the bifunctional device was analyzed in detail.And 3.3 folds of luminance from 2499 to 8233 cd/m² was achieved.?3?Based on the analysis of the influence of energy level and electron mobility on the performance of bifunctional devices,we continued to analyzing the effect of the different electron transport layer thicknesses on the device performance.Through the analysis of the experimental results,it is found that the change of the thickness of the electron transport layer not only affects the detection performance of the device,but also the luminescence performance of the device.And the maxture detectivity of8.0?10¹¹ Jones was achieved when the thickness of electron-transporting layer.In summary,the bifunctional devices with electroluminescence and ultraviolet photo detection properties were achieved by using different ETMs.The effect of ETMs on the devices was studied.This study provides an effective way on broadening the selection of ETMs and device architecture construction for the realization of high performance bifunctional devices.