Silica doped quantum dots film with enhanced light conversion efficiency for white light emitting diodes

Quantum dots (QDs) have broad prospect in illumination and display in the future with their high quantum efficiency, tunable color in the entire visible range, and excellent color rendering ability. QDs are generally prepared as remote films in white light-emitting diodes(WLED), which gives rise to low light conversion efficiency (LCE). In order to enhance the LCE of QD-converted WLED (QCWLED), a variety of mass fraction of micrometer-scale silica particles (SPs) were doped in QDs-PMMA films (QPFs) to prepare silica-QDs-PMMA films (SQPFs). Excited by identical blue light, the optical properties including optical power, reflectance, transmittance and collimating transmittance of the SQPFs and the QPF were measured by a double integrating sphere system, and their absorption coefficient, scattering coefficient and anisotropic coefficient were calculated by the inverse adding doubling algorithm (IADA). The effect of the SPs concentration on the optical properties of SQPFs was discussed. Results suggested that SQPFs possess higher LCE than the QPF and the LCE of the SQPFs increased gradually with the rise of the SPs mass fraction in the range from 0 % to 50 %. The absorption coefficient, scattering coefficient and anisotropy coefficient of the SQPFs were significantly related to the concentration of the SPs. Finally, the mechanism about how SPs work was analyzed.