Color-stable, reduced efficiency roll-off hybrid white organic light emitting diodes with ultra high brightness

High-brightness and color-stable two-wavelength hybrid white organic light emitting diodes (HWOLEDs) with the configuration of indium tin oxide (ITO)/ N, N, N', N'-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD): tetrafluoro-tetracyanoqino dimethane (F4-TCNQ)/N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine (NPB)/4,4-N,N-dicarbazolebiphenyl (CBP): iridium (III) diazine complexes (MPPZ)2Ir(acac)/NPB/2-methyl-9,10-di(2-naphthyl)anthracene (MADN): p-bis(p-N,N-di-phenyl-aminostyryl)benzene (DSA-ph)/ bis(10-hydroxybenzo[h] quinolinato)beryllium complex (Bebq2)/LiF/Al have been fabricated and characterized. The optimal brightness of the device is 69932 cd/m2 at a voltage of 13 V, and the Commission Internationale de l'Eclairage (CIE) chromaticity coordinates are almost constant during a large voltage change of 6–12 V. Furthermore, a current efficiency of 15.3 cd/A at an illumination-relevant brightness of 1000 cd/m2 is obtained, which rolls off slightly to 13.0 cd/A at an ultra high brightness of 50000 cd/m2 . We attribute this great performance to wisely selecting an appropriate spacer together with effectively utilizing the combinations of exciton-harvested orange-phosphorescence/ blue-fluorescence in the device. Undoubtedly, this is one of the most exciting results in two-wavelength HWOLEDs up to now.

[1]  Sujun Hu,et al.  Simultaneous Optimization of Charge‐Carrier Balance and Luminous Efficacy in Highly Efficient White Polymer Light‐Emitting Devices , 2011, Advanced materials.

[2]  Stephen R. Forrest,et al.  Efficient Organic Electrophosphorescent White‐Light‐Emitting Device with a Triple Doped Emissive Layer , 2004 .

[3]  V. Roy,et al.  Efficient White Organic Light‐Emitting Devices Based on Phosphorescent Platinum(II)/Fluorescent Dual‐Emitting Layers , 2007 .

[4]  Young Kwan Kim,et al.  Codoped spacer ratio effect of hybrid white organic light-emitting diodes , 2011 .

[5]  Junji Kido,et al.  Highly Efficient Organic Blue‐and White‐Light‐Emitting Devices Having a Carrier‐ and Exciton‐Confining Structure for Reduced Efficiency Roll‐Off , 2008 .

[6]  B. Ju,et al.  Balancing the white emission of OLED by a design of fluorescent blue and phosphorescent green/red emitting layer structures , 2009 .

[7]  Xiao-jun Liu,et al.  White organic light-emitting diodes based on a combined electromer and monomer emission in doubly-doped polymers , 2012 .

[8]  Dongge Ma,et al.  Achieving highly efficient white organic light-emitting diodes with reduced efficiency roll-off , 2009 .

[9]  Dongge Ma,et al.  Manipulating Charges and Excitons within a Single‐Host System to Accomplish Efficiency/CRI/Color‐Stability Trade‐off for High‐Performance OWLEDs , 2009 .

[10]  Gregor Schwartz,et al.  Harvesting Triplet Excitons from Fluorescent Blue Emitters in White Organic Light‐Emitting Diodes , 2007 .

[11]  Wu Xiaoming,et al.  White organic light-emitting device with both phosphorescent and fluorescent emissive layers , 2008 .

[12]  Stephen R. Forrest,et al.  Management of singlet and triplet excitons for efficient white organic light-emitting devices , 2006, Nature.

[13]  Young Kwan Kim,et al.  Ratio Effect of Codoped Spacer on Electroluminescent Characteristics of Hybrid White Organic Light-Emitting Diodes , 2010 .

[14]  Zai‐Quan Xu,et al.  Light out-coupling enhancement of organic light-emitting devices with microlens array , 2010 .

[15]  Gregor Schwartz,et al.  Triplet Harvesting in Hybrid White Organic Light‐Emitting Diodes , 2009 .

[16]  Y. Duan,et al.  Extremely low voltage and high bright p-i-n fluorescent white organic light-emitting diodes , 2008 .

[17]  Cheuk‐Lam Ho,et al.  Reduced efficiency roll-off in highly efficient and color-stable hybrid WOLEDs: The influence of triplet transfer and charge-transport behavior on enhancing device performance , 2010 .

[18]  Bin Li,et al.  White organic light-emitting devices with a bipolar transport layer between blue fluorescent and orange phosphorescent emitting layers , 2007 .

[19]  Gang Cheng,et al.  Improved efficiency for white organic light-emitting devices based on phosphor sensitized fluorescence , 2006 .

[20]  Gregor Schwartz,et al.  White organic light-emitting diodes with fluorescent tube efficiency , 2009, Nature.

[21]  Junbiao Peng,et al.  High-efficiency and good color quality white light-emitting devices based on polymer blend , 2009 .

[22]  M. Petty,et al.  Performance enhancement of white-electrophosphorescent devices incorporating a mixed-transition layer , 2008 .