White organic light-emitting diodes were fabricated by using 4,48-bis （2,28-diphenylvinyl）-1,18-biphenyl （DPVBi） as a dopant with a structure of ITO/4,4′-bis[N-（1-naphthyl-1-）-N-phenyl-amino]-biphenyl （NPB,50...White organic light-emitting diodes were fabricated by using 4,48-bis （2,28-diphenylvinyl）-1,18-biphenyl （DPVBi） as a dopant with a structure of ITO/4,4′-bis[N-（1-naphthyl-1-）-N-phenyl-amino]-biphenyl （NPB,50 nm）/NPB:DPVBi （molecular weight ratio 10∶1,30 nm）/tris-（8-hydroxyquinoline）aluminum（Alq3,20 nm）/LiF（1 nm）/Al.A broad emissive band with four major peaks of 438,464,496 and 520 nm was obtained by electroluminescence spectra,of which 438 nm-,464 nm-and 520 nm-peak come from emission of NPB,DPVBi and Alq3,respectively,and 496 nm-one resulted from the emissive superposition of three materials above.The emission from DPVBi was attributed to the charge trapping from NPB.The emission region was transferred partly from Alq3 to DPVBi-doped NPB by introducing the dopant DPVBi,which leads to emission of DPVBi and an enhanced emission from NPB.The maximum luminance and current efficiency were 4721 cd/m2 at 22 V and 0.80 cd/A at 5V,respectively.展开更多
A novel full color SOP(system on panel) AMOLED display based on the MIUC polycrystalline silicon TFT technique, and a new control circuit for the panel, which can deal with both VGA and DVI input signals have been dev...A novel full color SOP(system on panel) AMOLED display based on the MIUC polycrystalline silicon TFT technique, and a new control circuit for the panel, which can deal with both VGA and DVI input signals have been developed.To realize gray-scale a sub-frame technique has been designed and implemented by FPGA device,in which an I^2C module has been inserted.Through actual circuit,the whole design has been proven and the advantages of the SOP AMOLED display panel have been confirmed.展开更多
The experimental study on negative capacitance(NC) of various light-emitting diodes(LEDs) is presented.Experimental result shows that all LEDs display the NC phenomenon.The voltage modulated electroluminescence(VMEL) ...The experimental study on negative capacitance(NC) of various light-emitting diodes(LEDs) is presented.Experimental result shows that all LEDs display the NC phenomenon.The voltage modulated electroluminescence(VMEL) experiment confirms that the reason of negative capacitance is the strong recombination of the injected carriers in the active region of luminescence.The measures also verify that the dependence of NC on voltage and frequency in different LEDs is similar: NC phenomenon is more obvious with higher voltage or lower frequency.展开更多
In order to explain the phenomenon of negative capacitance(NC) in light emitting diodes LEDs,we present a new model based on local strong recombination in active region and firstly deduce the analytic expression of NC...In order to explain the phenomenon of negative capacitance(NC) in light emitting diodes LEDs,we present a new model based on local strong recombination in active region and firstly deduce the analytic expression of NC from continuity equation.The theoretical result indicates that the NC effect becomes stronger when the carrier recombination rate increases in a certain range,which is consistent with the experimental result.Accordingly,we confirm that the NC is caused by carrier recombination in active region instead of by other exterior factors.展开更多
The coupled DBR LED with one DBR for reflecting normal incidence light and the other for reflecting inclined incidence light has been grown by MOCVD. For improving the conventional DBR which was used to increase light...The coupled DBR LED with one DBR for reflecting normal incidence light and the other for reflecting inclined incidence light has been grown by MOCVD. For improving the conventional DBR which was used to increase light extraction efficiency in AlGaInP red light LED is analyzed. At 20 mA Dc injection current, the LED peak wave length is 630 nm, and the light intensity of on axis is 137 mcd. The output light power is 2.32 mW. The light intensity and output light power have been improved compared with the conventional LEDs.展开更多
文摘White organic light-emitting diodes were fabricated by using 4,48-bis （2,28-diphenylvinyl）-1,18-biphenyl （DPVBi） as a dopant with a structure of ITO/4,4′-bis[N-（1-naphthyl-1-）-N-phenyl-amino]-biphenyl （NPB,50 nm）/NPB:DPVBi （molecular weight ratio 10∶1,30 nm）/tris-（8-hydroxyquinoline）aluminum（Alq3,20 nm）/LiF（1 nm）/Al.A broad emissive band with four major peaks of 438,464,496 and 520 nm was obtained by electroluminescence spectra,of which 438 nm-,464 nm-and 520 nm-peak come from emission of NPB,DPVBi and Alq3,respectively,and 496 nm-one resulted from the emissive superposition of three materials above.The emission from DPVBi was attributed to the charge trapping from NPB.The emission region was transferred partly from Alq3 to DPVBi-doped NPB by introducing the dopant DPVBi,which leads to emission of DPVBi and an enhanced emission from NPB.The maximum luminance and current efficiency were 4721 cd/m2 at 22 V and 0.80 cd/A at 5V,respectively.
文摘A novel full color SOP(system on panel) AMOLED display based on the MIUC polycrystalline silicon TFT technique, and a new control circuit for the panel, which can deal with both VGA and DVI input signals have been developed.To realize gray-scale a sub-frame technique has been designed and implemented by FPGA device,in which an I^2C module has been inserted.Through actual circuit,the whole design has been proven and the advantages of the SOP AMOLED display panel have been confirmed.
基金This workis supported by the National Nature Science Founda-tion (Grant No.DMR-60376027)
文摘The experimental study on negative capacitance(NC) of various light-emitting diodes(LEDs) is presented.Experimental result shows that all LEDs display the NC phenomenon.The voltage modulated electroluminescence(VMEL) experiment confirms that the reason of negative capacitance is the strong recombination of the injected carriers in the active region of luminescence.The measures also verify that the dependence of NC on voltage and frequency in different LEDs is similar: NC phenomenon is more obvious with higher voltage or lower frequency.
基金This work was supported by the National Nature Science Foun-dation (Grant No.DMR-60376027) .
文摘In order to explain the phenomenon of negative capacitance(NC) in light emitting diodes LEDs,we present a new model based on local strong recombination in active region and firstly deduce the analytic expression of NC from continuity equation.The theoretical result indicates that the NC effect becomes stronger when the carrier recombination rate increases in a certain range,which is consistent with the experimental result.Accordingly,we confirm that the NC is caused by carrier recombination in active region instead of by other exterior factors.
基金supported by Beijing Science and Technology Committee (project number D0404003040221)
文摘The coupled DBR LED with one DBR for reflecting normal incidence light and the other for reflecting inclined incidence light has been grown by MOCVD. For improving the conventional DBR which was used to increase light extraction efficiency in AlGaInP red light LED is analyzed. At 20 mA Dc injection current, the LED peak wave length is 630 nm, and the light intensity of on axis is 137 mcd. The output light power is 2.32 mW. The light intensity and output light power have been improved compared with the conventional LEDs.
