We investigated the effects of pulsed current (PC) and direct current (DC) driving modes on the stability of organic light-emitting diodes with and without hole-injection layers (HILs).Two different HIL materials were...We investigated the effects of pulsed current (PC) and direct current (DC) driving modes on the stability of organic light-emitting diodes with and without hole-injection layers (HILs).Two different HIL materials were used:copper phthalocyanine (CuPc) and 4,4',4″-tris(3-methylphenylphenylamino)triphenylamine (m-MDTATA).It was found that the half-lives of devices using PC driving modes were different from those of comparable devices using DC driving modes.For the devices without HILs,with CuPc HILs and with MTDATA HILs,the half-lives of the devices were changed by factors of 1.91,1.41 and 0.86,respectively,when operated in PC rather than DC driving modes.Our analysis of the electrical characteristics of the corresponding hole-only devices showed that the number of holes injected into devices was greatly reduced by inserting an m-MTDATA layer compared with other designs.The results indicate that different ratios of injected electrons and holes can be obtained in these devices.Moreover,these ratios play a dominant role in the dependence of the stability of the device on the driving mode.展开更多
White organic light-emitting device (WOLEDs) employing molecular mixed host (MH) is demonstrated by spin-coating.The spin-coated film functions as light-emitting layer and hole transporting layer,with the former forme...White organic light-emitting device (WOLEDs) employing molecular mixed host (MH) is demonstrated by spin-coating.The spin-coated film functions as light-emitting layer and hole transporting layer,with the former formed by spin-coating solution containing MH of NPB (N.N'-Bis(naphthalene-1-yl)-N,N'-bis(phenyl)-benzidine) and MADN (2-methyl-9,10-di(2-naphthyl) anthracene),blue dye (4,4'-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl) and yellow dye (5,6,11,12-tetraphenylnaphacene).The performances of the devices made with different mixed ratio of MH are investigated.It is found that the device performances depends on the MH ratio,and under the optimal NPB:MADN ratio (60:40),the WOLEDs show a maximum luminance of 24 671 cd/m2 and a current efficiency of 5.8 cd/A for the practical luminance of 1000 cd/m2.The effect of MH ratio on device performances can be attributed to the difference of hole mobility between the NPB and MADN.展开更多
基金supported by the National Natural Science Foundation of China (10904122)
文摘We investigated the effects of pulsed current (PC) and direct current (DC) driving modes on the stability of organic light-emitting diodes with and without hole-injection layers (HILs).Two different HIL materials were used:copper phthalocyanine (CuPc) and 4,4',4″-tris(3-methylphenylphenylamino)triphenylamine (m-MDTATA).It was found that the half-lives of devices using PC driving modes were different from those of comparable devices using DC driving modes.For the devices without HILs,with CuPc HILs and with MTDATA HILs,the half-lives of the devices were changed by factors of 1.91,1.41 and 0.86,respectively,when operated in PC rather than DC driving modes.Our analysis of the electrical characteristics of the corresponding hole-only devices showed that the number of holes injected into devices was greatly reduced by inserting an m-MTDATA layer compared with other designs.The results indicate that different ratios of injected electrons and holes can be obtained in these devices.Moreover,these ratios play a dominant role in the dependence of the stability of the device on the driving mode.
基金supported by the National Basic Research Program of China (Grant No.2006CB921602)the Ministry of Education of China (Grant No.107100)the Program for New Century Excellent Talents in University and the Technology Program of Shaanxi Province (Grant No.2006K04-c25)
文摘White organic light-emitting device (WOLEDs) employing molecular mixed host (MH) is demonstrated by spin-coating.The spin-coated film functions as light-emitting layer and hole transporting layer,with the former formed by spin-coating solution containing MH of NPB (N.N'-Bis(naphthalene-1-yl)-N,N'-bis(phenyl)-benzidine) and MADN (2-methyl-9,10-di(2-naphthyl) anthracene),blue dye (4,4'-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl) and yellow dye (5,6,11,12-tetraphenylnaphacene).The performances of the devices made with different mixed ratio of MH are investigated.It is found that the device performances depends on the MH ratio,and under the optimal NPB:MADN ratio (60:40),the WOLEDs show a maximum luminance of 24 671 cd/m2 and a current efficiency of 5.8 cd/A for the practical luminance of 1000 cd/m2.The effect of MH ratio on device performances can be attributed to the difference of hole mobility between the NPB and MADN.
