Charge trap assisted high efficiency in new polymer-blend based light emitting diodes

Research output: Contribution to journalArticlepeer-review


  • M. U. Hassan
  • Yee Chen Liu
  • Kamran Ul Hasan
  • Jui Fen Chang
  • R. H. Friend

External organisations

  • COMSATS Institute Information Technology
  • Centers of Excellence in Science and Applied Technologies (CESAT)
  • Nanotechnology Laboratory
  • National Central University Taiwan
  • University of Cambridge


Polymer blend system, F81-xSYx, based on mixture of poly (9,9-dioctylfluorene) (F8) and a poly (para-phenylenevinylene) (PPV) copolymer, superyellow (SY), has been proven to be a high performance blend material in polymer light emitting diode (PLED). This blend system exhibits luminance (L) >104cdm-2, luminous efficiency (η) >21cdA-1 and low operating voltage (V) ~3-10V. The performance can be credited to the large difference (~0.6eV) between the highest occupied molecular orbital (HOMO) levels of F8 (~5.8eV) and SY (~5.2eV), where, SY molecules serve as hole-traps in the F8 host polymer and reduce their mobility. This dictates a balanced charge injection into the emissive layer and results in overall increase in the device performance.


Original languageEnglish
Pages (from-to)62-70
Number of pages9
JournalNano Energy
Early online date13 Jan 2016
Publication statusPublished - Mar 2016


  • Light emitting diodes, Poly(para-phenylenevinylenes), Polyfluorenes, Polymer-blend diodes