Selective Gain in a Periodic Array of Nano-organic Light-Emitting Diodes

We report nanoscale organic light-emitting diodes (OLEDs) arranged periodically into a large-area array, which produces an amplified emission with a selected spectrum in a narrow band. These nano-OLEDs share a common active layer of super yellow light-emitting PPV copolymer (SY-PPV), which acts both as a waveguide and as a gain channel for the light-emitting signals. The periodic structure supplies Bragg-like diffraction of the emission from SY-PPV under electrical excitation so that the electroluminescence signal is coupled into and confined in the SY-PPV waveguide. During propagation, the waveguide resonance mode interacts with the nano-OLED region and gains amplification. Both the waveguide resonance mode and the output coupling process have strong spectral selectivity, so that the amplification is observed within a spectrum as narrow as 32 nm at FWHM. Such a nano-OLED design not only defines a new scheme of nano-OLEDs, but also proposes potential approaches for electrically pumped organic lasers.