Structurally engineered colloidal quantum dot phosphor using TiO2 photonic crystal backbone

Abstract

Photonic crystal (PhC) phosphor, in which the phosphor material is periodically modulated for an enhancement in color-conversion efficiency via resonant absorption of excitation photons, is a paradigm-shifting structural phosphor platform. Two-dimensional (2D) square-lattice PhC phosphor is currently considered the most advanced platform because of not only its high efficiency, but also its immunity to excitation polarization. In the present study, two major modifications are made to further improve the performance of the 2D PhC phosphor: increasing the refractive index contrast and planarizing the surface. The index contrast is improved by replacing the PhC backbone material with TiO2 whereas the surface planarization is achieved by removing excessive colloidal quantum dots from the surface. In comparison with the reference phosphor, the upgraded PhC phosphor exhibits ~59 times enhanced absorption (in simulations) and ~7 times enhanced emission (in experiments), both of which are unprecedentedly high. Our results not only brighten the viability and applicability of the PhC phosphor but also spur the phosphor development through structural engineering of phosphor materials.

A high-performance UV photodetector with superior responsivity enabled by a synergistic photo/thermal enhancement of localized surface plasmon resonance

“…10,11 Among them, titania (TiO 2 ) has attracted significant attention due to its unique superiority with regard to chemical and thermal stability, high temperature resistance, and excellent photoelectric properties. 12 The wide-ranging applications of TiO 2 nanostructures have enabled researchers to realize the significance of improving the optoelectronic performance of UV photodetectors.…”

Resonant cavity phosphor

“…We previously proposed and demonstrated the concept of structurally engineered phosphors 15 – 18 , in which the phosphor material was carved into a nanophotonic structure to significantly increase A (while η int and η oc remained unaltered). More specifically, we incorporated CQDs, which served as the phosphor material, into a prefabricated planar photonic crystal (PhC) backbone such that the Γ-point ( ) band-edge mode(s) associated with the resultant PhC structure was tuned at the wavelength for CQD excitation.…”

“…Nonetheless, RC has never been explored or considered as a platform for phosphors. The RC phosphor (RC-PSP) proposed herein differs from the PhC phosphor previously developed by us 15 – 18 ; it utilises a localised vertical cavity mode whereas the PhC phosphor relies on a periodic and extended in-plane band-edge mode. Furthermore, the RC-PSP is superior to the PhC phosphor in terms of both structure and performance.…”

Building an optics and photonics research ecosystem in South Korea: Collaborative innovation between academia and industry

“…1 ). This issue covers a wide range of topics in photonics including biomedical applications 6 – 8 , imaging 9 – 11 , micro light emitting diodes (μLED) 12 , quantum dot emitters 13 , deformable displays 14 , thin-flat optics 15 , 16 , radiative cooling 17 , and 2D optical devices 18 – 20 . Additionally, we introduce upcoming disruptive photonic applications with periodically arranged structures and their integration with conventional optics 15 , 21 .…”

“…This approach may significantly improve the efficiency of electronic sensing technology in terms of cost, space, and power consumption. Meanwhile, a paradigm-shifting photonic crystal (PhC) phosphor platform has been further improved by increasing the refractive index contrast and planarizing the surface 13 . The upgraded PhC phosphor exhibits unprecedentedly high absorption and emission efficiency, which may further spur the development of structural engineering of phosphor materials.…”