Twisted dendrons for highly luminescent green emissive phosphorescent dendrimers

A new class of twisted rigid biphenyl-based dendrons with t-butyl surface groups have been prepared and attached to a green emissive fac-tris(2-phenylpyridyl)iridium(III) core. Both singly (one dendron per ligand) and doubly (two dendrons per ligand) dendronised first generation dendrimers were prepared. In both cases the solution photoluminescence quantum yields (PLQYs) were over 10% higher than the equivalent dendrimers comprised of non-rigid biphenyl-dendrons and the same core, with the doubly dendronised compound having an almost quantitative PLQY. However, for both materials there was significant reduction in the PLQY in the solid-state indicating that while the t-butyl groups can provide a degree of solubility they do not shield the emissive core as well as surface groups such as 2-ethylhexyloxy, which have greater length. When the doubly dendronised material was blended with 4,4′,4′′-tris(carbazol-9-yl)triphenylamine the film PLQY approached that of the solution measurement and simple two-layer devices comprised of the emissive layer and an electron transport/hole-blocking layer of 1,3,5-tris(3-pyridyl-3-phenyl)benzene reached a maximum brightness of ≈10 000 cd m−2 and external quantum efficiency of 16.3%, corresponding to an out-coupling efficiency of around 20%.

[1]  Jinshan Wang,et al.  Dendritic Self-Host Phosphorescent Iridium Materials for High-Efficiency Organic Light-Emitting Diodes , 2018 .

[2]  Baohua Zhang,et al.  Improving the Power Efficiency of Solution‐Processed Phosphorescent WOLEDs with a Self‐Host Blue Iridium Dendrimer , 2017 .

[3]  Lixiang Wang,et al.  Solution processable red iridium dendrimers containing oligocarbazole dendrons for efficient nondoped and doped phosphorescent OLEDs , 2017 .

[4]  Jinshan Wang,et al.  Dendritic Self-Host Iridium Phosphorescent Materials for High-Efficiency and Long Life-Time Organic Light-Emitting Diodes , 2017 .

[5]  Baohua Zhang,et al.  Solution-processed multilayer green electrophosphorescent devices with self-host iridium dendrimers as the nondoped emitting layer: achieving high efficiency while avoiding redissolution-induced batch-to-batch variation. , 2017, Chemical communications.

[6]  Soon-Ki Kwon,et al.  Ultrahigh-efficiency solution-processed simplified small-molecule organic light-emitting diodes using universal host materials , 2016, Science Advances.

[7]  Junji Kido,et al.  Solution‐Processed White Phosphorescent Tandem Organic Light‐Emitting Devices , 2015, Advanced materials.

[8]  C. Adachi,et al.  Highly efficient electroluminescence from purely organic donor–acceptor systems , 2015 .

[9]  W. Wong,et al.  Recent Advances in Solution-Processable Dendrimers for Highly Efficient Phosphorescent Organic Light-Emitting Diodes (PHOLEDs) , 2015 .

[10]  Bo Chen,et al.  Self-host blue-emitting iridium dendrimer with carbazole dendrons: nondoped phosphorescent organic light-emitting diodes. , 2014, Angewandte Chemie.

[11]  Tobias D. Schmidt,et al.  Device efficiency of organic light‐emitting diodes: Progress by improved light outcoupling , 2013 .

[12]  P. Meredith,et al.  Facile iterative synthesis of biphenyl dendrons with a functionalized focus. , 2010, Organic letters.

[13]  S. Gambino,et al.  Light-emitting dendrimer film morphology: A neutron reflectivity study , 2010 .

[14]  Z. Bian,et al.  Functional IrIII Complexes and Their Applications , 2010, Advanced materials.

[15]  Ruth E. Harding,et al.  High-triplet-energy dendrons: enhancing the luminescence of deep blue phosphorescent iridium(III) complexes. , 2009, Journal of the American Chemical Society.

[16]  Ruth E. Harding,et al.  The development of phenylethylene dendrons for blue phosphorescent emitters , 2009 .

[17]  S. Gambino,et al.  Control of Charge Transport in Iridium(III) Complex‐Cored Carbazole Dendrimers by Generation and Structural Modification , 2009 .

[18]  Ruth E. Harding,et al.  Solution‐Processible Phosphorescent Blue Dendrimers Based on Biphenyl‐Dendrons and Fac‐tris(phenyltriazolyl)iridium(III) Cores , 2008 .

[19]  M. Thompson.  The Evolution of Organometallic Complexes in Organic Light-Emitting Devices , 2007 .

[20]  I. Samuel,et al.  The Development of Light‐Emitting Dendrimers for Displays , 2007 .

[21]  E. Namdas,et al.  The synthesis and properties of iridium cored dendrimers with carbazole dendrons , 2006 .

[22]  E. Namdas,et al.  Encapsulated Cores: Host‐Free Organic Light‐Emitting Diodes Based on Solution‐Processible Electrophosphorescent Dendrimers , 2005 .

[23]  H. Nishide,et al.  Poly(thiaheterohelicene): a stiff conjugated helical polymer comprised of fused benzothiophene rings. , 2005, Organic letters.

[24]  E. Namdas,et al.  Synthesis and properties of highly efficient electroluminescent green phosphorescent iridium cored dendrimers , 2003 .

[25]  I. Samuel,et al.  Structure-property relationships in conjugated molecules , 2001 .

[26]  W. Marshall,et al.  New, efficient electroluminescent materials based onorganometallic Ir complexes , 2001 .

[27]  A. Spek,et al.  Synthesis of Novel Phosphaalkene-Based Bidentate Ligands Mes*(Me)P=CH(3-R-Ar) (R = Pyridyl, Carbaldimino) and Formation of Three-Membered Palladacycles Mes*(Me)P-CH(3-R-Ar)-PdCl by Carbapalladation of the P=C Double Bond , 1999 .

[28]  S. Forrest,et al.  Highly efficient phosphorescent emission from organic electroluminescent devices , 1998, Nature.

[29]  M. V. Kulikova,et al.  Photophysics, photochemistry and electrochemistry of mixed-ligand platinum(II) complexes with 2-phenylpyridine and 2-(2′-thienyl)pyridine as cyclometalating ligands , 1997 .

[30]  Ifor D. W. Samuel,et al.  Measurement of absolute photoluminescence quantum efficiencies in conjugated polymers , 1995 .

[31]  J. Demas,et al.  Measurement of photoluminescence quantum yields. Review , 1971 .