Mesostructured Composite Materials with Electrically Tunable Upconverting Properties.
A promising approach of designing mesostructured materials with novel physical behavior is to combine unique optical and electronic properties of solid nanoparticles with long-range ordering and facile response of soft matter to weak external stimuli. Here, orientationally ordered nematic liquid crystalline dispersions of rod-like upconversion nanoparticles are designed, practically realized, and characterized. Boundary conditions on particle surfaces, defined through surface functionalization, promote spontaneous unidirectional self-alignment of the dispersed rod-like nanoparticles, mechanically coupled to the molecular ordering direction of the thermotropic nematic liquid crystal host. As host is electrically switched at low voltages ≈ 1 V, nanorods rotate, yielding tunable upconversion and polarized luminescence properties of the composite. Spectral and polarization dependencies are characterized and explained through invoking models of electrical switching of liquid crystals and upconversion dependence on crystalline matrices of nanorods, and their potential practical uses are discussed.
Department of Physics and Department of Electrical, Computer and Energy Engineering, Materials Science and Engineering Program, and Liquid Crystal Materials Research Center, University of Colorado, Boulder, CO, 80309, USA.
Haridas
H
Mundoor
Department of Physics and Department of Electrical, Computer and Energy Engineering, Materials Science and Engineering Program, and Liquid Crystal Materials Research Center, University of Colorado, Boulder, CO, 80309, USA.|Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, CO, 80309, USA.
Ivan I
II
Smalyukh
electric switching; liquid crystals; orientational order; polarized luminescence; upconversion, nanoparticles