(372c) Encapsulated Quantum Dots in Sol-Gel and Polymer Matrices As Optical Filtering and Wavelength-Shifting Materials

Encapsulated Quantum Dots in Sol-Gel and Polymer Matrices


as Optical Filtering and Wavelength-Shifting Materials

Michael Z. Hu and Zane W. Bell

Quantum-dot nanoparticles of ZnO and CdS were chemically
synthesized and then encapsulated inside a silica sol-gel monolithic solid or
polymer (PMMA) matrices. The nanoparticles serve as the ?guest? inside the host
matrices. Nanoparticles are developed with tunable optical properties (i.e.,
UV-VIS absorption and photoluminecent emission). The guest-host composite
optical materials were engineered to provide the task-specific absorption
cutoff sharpness and peak position (for optical filtering), or alternatively,
provide desirable absorption and emission peaks (for wavelength-shifting). Such
developed optical materials are strategically designed for optical signal
management such as for nuclear detection or other optical sensing applications.
One example of optical signal management is on the discrimination of optical
signals induced from neutron and gamma-ray events in a scintillating crystal.  Different
detector crystals generate different optical signals that requires tunability
of optical filtering or wavelength-shifting to meet the specific signal
management needs. Qunatum-dot materials offer such optical tunability. However,
challenges remains in the selection of composition, size and compatible
encapsulation inside a solid matrix platform. Besides absorption peak position
(cutoff) control, future work needs to explore the possibility of quenching of
photoluminecense (for filter development) or simultaneously tuning the
selective absorption and emission (for wavelength-shifter development).