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Hyperbranched Polymers with High Transparency and Inherent High Refractive Index for Application in Organic Light‐Emitting Diodes
Author(s) -
Wei Qiang,
Pötzsch Robert,
Liu Xiaoling,
Komber Hartmut,
Kiriy Anton,
Voit Brigitte,
Will PaulAnton,
Lenk Simone,
Reineke Sebastian
Publication year - 2016
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201504914
Subject(s) - materials science , oled , high refractive index polymer , refractive index , thermal stability , optoelectronics , polymer , diode , chemical engineering , nanotechnology , composite material , layer (electronics) , engineering
Hyperbranched polyvinylsulfides have been prepared through a facile, metal‐free, radical induced “A 2 +B 3 ” thiol‐yne polymerization of 1,3,5‐tris(naphthalylethynyl) benzene and 1,4‐dithiolbenzene with three different input ratios. The resulting polymers exhibit excellent optical properties like high transparency and very high refractive index (RI) of up to 1.7839, combined with high thermal stability ( T d5% up to 420 °C) and excellent solution processability. These properties make them ideal candidates as high RI polymeric materials (HRIP) in connection with light out‐coupling schemes for organic light‐emitting diodes (OLEDs). A series of hyperbranched HRIPs with varying monomer compositions have been compared in their optical properties. Finally, phosphorescent monochrome OLEDs are fabricated on top of HRIP layers to test the compatibility of HRIPs with state‐of‐the‐art OLEDs. The results show that the HRIPs do not deteriorate the performance of the OLEDs while maintaining external quantum efficiencies of over 20% for phosphorescent red OLEDs. These results open a pathway toward alternative, low‐cost, and scalable out‐coupling concepts through refractive index matching of the OLED materials and the HRIPs presented.