Efficient infrared electroluminescent devices using solution-processed colloidal quantum dots

We report efficient electroluminescence in the near-infrared from PbS-MEH-PPV (poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene)) large-area, solution-cast nanocomposite devices. We employ multivariate optimization of the structural and materials components that govern the radiative, energy-transfer, and bipolar-injection efficiencies into the devices. As a result, we report an external electroluminescence quantum efficiency of 0.27%, which corresponds to an internal electroluminescence quantum efficiency of 1.9%. The very best devices exhibit internal-radiative-efficiency-limited performance and not transport- or capture-limited performance, indicating that further gains in efficiency may be achieved if the internal radiative efficiency of the nanocrystal-polymer composite can be further increased without compromising transfer and device bipolar-injection efficiency.