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.
- Light emitting diodes
- Polymer-blend diodes