Highly-efficient broadband waveguide outcoupling in light-emitting diodes with self-organized polymer blends

Self-organized, two-dimensional micron-scale photonic structures have been fabricated within the emissive layer of polymer blend light-emitting diodes (LEDs). The relief-and-phase grating is achieved by phase separation of two semiconducting polymers directed by a surface chemical pattern. Short-wavelength oscillations are found pinned (and are thus phase-locked) to the domain boundaries. These high-frequency harmonics mimic short-period gratings in providing efficient waveguide outcoupling but without spectral dispersion. This provides a general way to harness the waveguide modes trapped in polymer LEDs, doubling their external quantum and power efficiencies while maintaining spectral integrity with viewing angle. (C) 2004 American Institute of Physics.