It is demonstrated that barium and aluminum alloy synthesized by melting in a glass tube under low vacuum is applicable for organic laser emitting diodes(LEDs)as a thin film cathode.The alloy film obtained by the ther...It is demonstrated that barium and aluminum alloy synthesized by melting in a glass tube under low vacuum is applicable for organic laser emitting diodes(LEDs)as a thin film cathode.The alloy film obtained by the thermal evaporation of pre-synthesized alloy is used in a single-boat organic LED device with the structure:indium tin oxide(ITO)/4,4'-bis[N−(1-naphthyl)-N−phenylamino]biphenyl(NPB)/tris-(8-hydroxyquinoline)aluminum(Alq3)/barium:aluminum alloy.The experimental results show that devices with this alloy film cathode exhibit better current density-voltage-luminance characteristics than those with a conventional pure Al cathode,and more weight of barium in aluminum leads to better performance of the devices.Characteristics of current density versus voltage for the electron-only devices are fitted by the Richardson–Schottky emission model,indicating that the electron injection barrier has a decrease of about 0.3 eV by this alloy cathode.展开更多
The inverted bottom-emitting organic light-emitting devices(IBOLEDs)were prepared,with the structure of ITO/Al(x nm)/Li F(1 nm)/Bphen(40 nm)/CBP:GIr1(14%):R-4b(2%)(10 nm)/BCP(3 nm)/CBP:GIr1(14%):R-4b(2%)(20 nm)/TCTA(1...The inverted bottom-emitting organic light-emitting devices(IBOLEDs)were prepared,with the structure of ITO/Al(x nm)/Li F(1 nm)/Bphen(40 nm)/CBP:GIr1(14%):R-4b(2%)(10 nm)/BCP(3 nm)/CBP:GIr1(14%):R-4b(2%)(20 nm)/TCTA(10 nm)/NPB(40 nm)/Mo O_3(40 nm)/Al(100 nm),where the thickness of electron injection layer Al(x)are 0 nm,2 nm,3 nm,4 nm and 5 nm,respectively.In this paper,the electron injection condition and luminance properties of inverted devices were investigated by changing the thickness of Al layer in Al/Li F compound thin film.It turns out that the introduction of Al layer can improve electron injection of the devices dramatically.Furthermore,the device exerts lower driving voltage and higher current efficiency when the thickness of electron injection Al layer is3 nm.For example,the current efficiency of the device with 3-nm-thick Al layer reaches 19.75 cd·A^(-1) when driving voltage is 7 V,which is 1.24,1.17 and 17.03 times larger than those of the devices with 2 nm,4 nm and 5 nm Al layer,respectively.The device property reaches up to the level of corresponding conventional device.In addition,all inverted devices with electron injection Al layer show superior stability of color coordinate due to the adoption of co-evaporation emitting layer and BCP spacer-layer,and the color coordinate of the inverted device with 3-nm-thick Al layer only changes from(0.580 6,0.405 6)to(0.532 8,0.436 3)when driving voltage increases from 6 V to 10 V.展开更多
基金by the National Natural Science Foundation of China under Grant No 61076066the Doctor Foundation of the Shaanxi University of Science and Technology(No BJ09-07).
文摘It is demonstrated that barium and aluminum alloy synthesized by melting in a glass tube under low vacuum is applicable for organic laser emitting diodes(LEDs)as a thin film cathode.The alloy film obtained by the thermal evaporation of pre-synthesized alloy is used in a single-boat organic LED device with the structure:indium tin oxide(ITO)/4,4'-bis[N−(1-naphthyl)-N−phenylamino]biphenyl(NPB)/tris-(8-hydroxyquinoline)aluminum(Alq3)/barium:aluminum alloy.The experimental results show that devices with this alloy film cathode exhibit better current density-voltage-luminance characteristics than those with a conventional pure Al cathode,and more weight of barium in aluminum leads to better performance of the devices.Characteristics of current density versus voltage for the electron-only devices are fitted by the Richardson–Schottky emission model,indicating that the electron injection barrier has a decrease of about 0.3 eV by this alloy cathode.
基金supported by the National Natural Science Foundation of China(Nos.61076066 and 61605105)the Shaanxi Science&Technology Development Program(No.2011KTCQ01-09)
文摘The inverted bottom-emitting organic light-emitting devices(IBOLEDs)were prepared,with the structure of ITO/Al(x nm)/Li F(1 nm)/Bphen(40 nm)/CBP:GIr1(14%):R-4b(2%)(10 nm)/BCP(3 nm)/CBP:GIr1(14%):R-4b(2%)(20 nm)/TCTA(10 nm)/NPB(40 nm)/Mo O_3(40 nm)/Al(100 nm),where the thickness of electron injection layer Al(x)are 0 nm,2 nm,3 nm,4 nm and 5 nm,respectively.In this paper,the electron injection condition and luminance properties of inverted devices were investigated by changing the thickness of Al layer in Al/Li F compound thin film.It turns out that the introduction of Al layer can improve electron injection of the devices dramatically.Furthermore,the device exerts lower driving voltage and higher current efficiency when the thickness of electron injection Al layer is3 nm.For example,the current efficiency of the device with 3-nm-thick Al layer reaches 19.75 cd·A^(-1) when driving voltage is 7 V,which is 1.24,1.17 and 17.03 times larger than those of the devices with 2 nm,4 nm and 5 nm Al layer,respectively.The device property reaches up to the level of corresponding conventional device.In addition,all inverted devices with electron injection Al layer show superior stability of color coordinate due to the adoption of co-evaporation emitting layer and BCP spacer-layer,and the color coordinate of the inverted device with 3-nm-thick Al layer only changes from(0.580 6,0.405 6)to(0.532 8,0.436 3)when driving voltage increases from 6 V to 10 V.
