3 / 2017-04-01 19:02:19

Optical Micro-Resonators Based on Reactive-Mesogen Doped with Quantum-Dots for Color Elements

13355,Quantum dot

Recently, structural color elements have been extensively studied owing to the superior reliability and the stability in comparison to conventional color pigments. Particularly, an optical micro-resonator type is promising for the realization of the structure coloration since it allows the high optical efficiency and the polarization-independent optical property in a simple metal-dielectric-metal (MIM) configuration. It is desirable to improve the transmission of the micro-resonators for use as color filters, color image storage, and sensors. Several approaches such as an optical path control layer, a nano-porous structure, and a nano-grating structure have been suggested but they suffer from the peak shift of the transmittance due to the structural change or an additional structure in the MIM configuration. Moreover, a complex fabrication process is inevitably involved. In this work, we demonstrate a micro-resonator with spectral overlap between the selective transmittance of the optical micro-resonator and the photoluminescence (PL) spectrum of quantum dots (QDs) in a dielectric layer so as to improve the transmittance without a peak shift. In order to construct a resonant cavity between two metallic layers, a mixture of reactive-mesogens and QDs were slit-coated on an alignment layer which promoted the vertical alignment of mesogens. The resonant cavity with green QDs showed about 20% higher transmittance than that of a conventional MIM cavity at the peak wavelength of 530 nm and no peak shift. Our QD-dispersion approach would provide simple design of an optical micro-resonator with high transmission for a variety of applications including displays and coloration devices.
This work was supported in part by Samsung Display Company and BK 21 Program of Ministry of Education of Korea.