Polymer:quantum dot (QD) composites show enhanced optical and electronic properties. In this study, polymer light-emitting diodes (PLEDs) were fabricated and characterized using poly[2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylenevinylene] end capped with polyhedral oligomeric silsesquioxanes (MEH-PPV-POSS) as a luminescent polymer host and copper indium disulfide (CuInS2) QDs as a dopant. The emitted light originates from MEH-PPV-POSS. Incorporation of CuInS2 QDs into polymer matrix until certain amounts improved the device performance in terms of electroluminescence (EL) intensity, luminance, current and power efficiency compared to that of the undopped device. The improvement is remarkable when the QD concentration is 0.3 wt% in the composite. We demonstrate that CuInS2 QDs provide a better balance of charge carriers and prevent the formation of polymeric aggregates. (C) 2010 Elsevier B.V. All rights reserved.