Greatly decreased redshift and largely enhanced refractive index of mono-dispersed ZnO-QD/silicone nanocomposites

The luminescence behavior of quantum dots (QDs) has been demonstrated to be size-dependent and the alternation of surroundings from solvent to matrix normally leads to large redshifts due to the unavoidable occurrence of QD aggregates, which is detrimental to the successful application of QDs in light emitting devices (LEDs). In this study, a simple solvent mixing method is demonstrated for the fabrication of transparent silicone nanocomposites with greatly decreased redshift and largely enhanced refractive index. By silane surface modification of the ZnO-QDs, the dispersion of QDs in the silicone resin can be well controlled and the emission wavelength of the QDs can be nearly precisely determined with a maximum redshift of 4 nm from ethanol solvent to silicone resin matrix. Compared to the un-modified ZnO QD case, the redshifts have been dramatically decreased. In addition, the as-fabricated ZnO-QD/silicone nanocomposites exhibit a high visible light transparency while the diameter of ZnO-QDs varies from 1.8 nm to 4.5 nm. Moreover, by the incorporation of ZnO-QDs at a low content up to 1.0 wt%, the refractive index of the silicone resin is largely enhanced from 1.42 to 1.56. The current methodology is quality-controllable, cost-effective and environment-friendly and thus is applicable for the massive application of QD/silicone nanocomposites in LEDs.