摘要
Efficient white-polymer-light-emitting devices (WPLEDs) have been fabricated with a single emitting layer containing a hole-transporting host polymer,poly(N-vinylcarbzole),and an electron-transporting auxiliary,1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]-phenylene,codoped with two phosphorescent dyes:Iridium(III)bis (2-(4,6-difluorophenyl)-pyridinato-N,C2') picolinate (FIrpic) and home-made Ir-G2 for blue and red emission,respectively.With the structure of ITO/PEDOT:PSS 4083(40 nm)/emission layer(80 nm)/Ba(4 nm)/Al(120 nm),the device showed a maximal luminous efficiency (LE) of 13.5 cd A-1(corresponding to an external quantum efficiency (EQE) of 6.8%),and a peak power efficiency (PE) of 6.5 lm W-1 at 6.0 V.Meanwhile,the device exhibited pure white emission with Commission Internationale de l'Eclairage (CIE) coordinates of (0.34,0.35) at a current density of 12 mA cm-2,which is very close to the equi-energy white point with CIE coordinates of (0.33,0.33).The device performance can be further optimized when more balanced hole/electron injection is achieved by incorporating a lower conducting type anode buffer layer (PEDOT:PSS) and incorporating poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorenene)-alt-2,7-(9,9-dioctyfluorene)] (PFN) as an electron injection layer at the cathode.The optimized device showed an LE of 24.6 cd A-1 (with an EQE of 14.1%),while the peak power efficiency reached 12.66 lm W-1.Moreover,the WPLEDs showed good electroluminescence (EL) stability over a wide range of operating current density and luminance.
Efficient white-polymer-light-emitting devices （WPLEDs） have been fabricated with a single emitting layer containing a hole-transporting host polymer,poly（N-vinylcarbzole）,and an electron-transporting auxiliary,1,3-bis[（4-tert-butylphenyl）-1,3,4-oxadiazolyl]-phenylene,codoped with two phosphorescent dyes：Iridium（III）bis （2-（4,6-difluorophenyl）-pyridinato-N,C2＇） picolinate （FIrpic） and home-made Ir-G2 for blue and red emission,respectively.With the structure of ITO/PEDOT：PSS 4083（40 nm）/emission layer（80 nm）/Ba（4 nm）/Al（120 nm）,the device showed a maximal luminous efficiency （LE） of 13.5 cd A-1（corresponding to an external quantum efficiency （EQE） of 6.8%）,and a peak power efficiency （PE） of 6.5 lm W-1 at 6.0 V.Meanwhile,the device exhibited pure white emission with Commission Internationale de l＇Eclairage （CIE） coordinates of （0.34,0.35） at a current density of 12 mA cm-2,which is very close to the equi-energy white point with CIE coordinates of （0.33,0.33）.The device performance can be further optimized when more balanced hole/electron injection is achieved by incorporating a lower conducting type anode buffer layer （PEDOT：PSS） and incorporating poly[（9,9-bis（3＇-（N,N-dimethylamino）propyl）-2,7-fluorenene）-alt-2,7-（9,9-dioctyfluorene）] （PFN） as an electron injection layer at the cathode.The optimized device showed an LE of 24.6 cd A-1 （with an EQE of 14.1%）,while the peak power efficiency reached 12.66 lm W-1.Moreover,the WPLEDs showed good electroluminescence （EL） stability over a wide range of operating current density and luminance.
基金
Fund of Ministry of Education of China (20090172120012)
the National Basic Research Program of Chima (2009CB623602)
the National Natural Science Foundation of China (60906032)
the Fundamental Research Funds for the Central Universities for the financial support. Wong W.-Y. thanks the Hong Kong Research Grants Council (HKBU202709)
the University Grants Committee of HKSAR,China (AoE/P-03/08)
Hong Kong Baptist University (FRG2/08-09/111)
the Croucher Foundation for the Croucher Senior Research Fellowship
