Abstract
Quantum dots (QDs) have received considerable attention in information displays owing to their high quantum yield, high colour purity and low-cost fabrication. However, light emission for ultra-thin QD films with low mass percentage of QDs still need to be improved because the blue light can directly transmit the films, leading to insufficient energy to excite the QDs. In this study, we report QD films based on a poly(zinc methacrylate) coating with alloyed green-emitting CdZnSeS/ZnS quantum dots (QDs@PZnMA) together with high refractive-index BaTiO3 nanoparticles to enhance the scattering coefficient of the QD films. Results demonstrate a 7.5-fold increase in the absorption coefficient, 11.3-fold increase in the scattering coefficient, 8.5-fold increase in the optical density (OD) and 8.6-fold increase in the green-light emission of QD films, compared with films that have the same mass percentage of pristine QDs. This approach provides a promising strategy for developing QD optical films with high scattering and enhanced light emission for flexible displays.
Highlights
Colloidal quantum dots (QDs), cadmium-based Quantum dots (QDs), have been intensively studied as light-conversion materials in lighting and display applications because of their narrow emission band, high colour purity, stability and tunable emission wavelength based on quantum con nement effects.[1,2,3,4,5,6,7] Most QD televisions currently available in the market use QD lms located on top of the light-guide plate
We report QD films based on a poly(zinc methacrylate) coating with alloyed green-emitting CdZnSeS/ZnS quantum dots (QDs@PZnMA) together with high refractive-index BaTiO3 nanoparticles to enhance the scattering coefficient of the QD films
The green-light conversion lms were fabricated based on a poly(zinc methacrylate) coating with alloyed greenemitting CdZnSeS/ZnS QDs (QDs@PZnMA) because the S atoms on QDs can act as binding site for Zn atoms in zinc methacrylate, monoliths of which enhanced the scattering coefficient, optical density (OD) and the green-light emission, which was further enhanced using high-refractive-index BaTiO3 nanoparticles
Summary
Scattering can alter the optical path and incident angle of the emitted light to increase internal re ection so that light emission of the optical lm is enhanced through enhanced absorption for excitation photons.[9,10] Li et al showed that an eight-fold increase in the photoluminance (PL) emission of QD lms can be obtained by attaining high re ectivity of the exciting light through photonic crystal structures on InGaN-based LED chips.[11]. Unlike the traditional micron-sized phosphors possessing the scattering properties themselves,[14,15] the blue. To solve the above-mentioned problems of bluelight leakage and insufficient absorption for blue light by QDs, high-refractive-index BaTiO3 nanoparticles were selected as the scattering media to fabricate QD thin lms, as shown in Scheme 1. The green-light conversion lms were fabricated based on a poly(zinc methacrylate) coating with alloyed greenemitting CdZnSeS/ZnS QDs (QDs@PZnMA) because the S atoms on QDs can act as binding site for Zn atoms in zinc methacrylate, monoliths of which enhanced the scattering coefficient, optical density (OD) and the green-light emission, which was further enhanced using high-refractive-index BaTiO3 nanoparticles. Results showed that the light-scattering function played an important role in enhancing the light emission of QD lms
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