Publication

Abstract : We present a dual-resonance nanostructure made of a titanium dioxide (TiO2) subwavelength grating to enhance the color downconversion efficiency of CdxZn1-xSeyS1-y colloidal quantum dots (QDs) emitting at similar to 530 nm when excited with a blue light at similar to 460 nm. A large mode volume can be created within the QD layer by the hybridization of the grating resonances and waveguide modes, resulting in large absorption and emission enhancements. Particularly, we achieved polarized light emission with a maximum photoluminescence enhancement of similar to 140 times at a specific angular direction and a total enhancement of similar to 34 times within a 0.55 numerical aperture (NA) of the collecting objective. The enhancement encompasses absorption, Purcell and outcoupling enhancements. We achieved a total absorption of 35% for green QDs with a remarkably thin color conversion layer of similar to 400 nm. This work provides a guideline for designing large-volume cavities for absorption/fluorescence enhancement in microLED display, detector, or photovoltaic applications.