Polarized Fluorescence from Vitrified Liquid Crystalline Films

1996 ◽  
Vol 425 ◽  
Author(s):  
Brooke M. Conger ◽  
H. Shi ◽  
S. H. Chen ◽  
T. Tsutsui
Keyword(s):  
Liquid Crystal ◽  
Linear Polarization ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Emission Spectra ◽  
Polarized Fluorescence ◽  
Circularly Polarized ◽  
Chiral Nematic ◽  
Polarization Factor ◽  
Crystalline Films

AbstractLinearly and circularly polarized photoluminescence (PL) were observed from neat vitrified liquid crystal (LC) films. Electronic properties of the compounds were investigated through measurement of absorption and emission spectra in solution and in film. The nematic film exhibited a polarization factor (linear polarization) of 2.8 at an order parameter of 0.70, whereas the chiral nematic film gave rise to an absolute dissymmetry factor (circular polarization) of 0.27 at an order parameter of 0.54.

Circularly polarized fluorescence from chiral nematic liquid crystalline films: theory and experiment

1998 ◽  
Vol 24 (2) ◽  
pp. 163-172 ◽  
Author(s):  
HONGQIN SHI ◽  
BROOKE M. CONGER ◽  
DIMITRIS KATSIS ◽  
SHAW H. CHEN
Keyword(s):  
Liquid Crystalline ◽  
Polarized Fluorescence ◽  
Circularly Polarized ◽  
Chiral Nematic ◽  
Crystalline Films ◽  
Theory And Experiment

scholarly journals Chiral Liquid Crystalline Electronic Systems

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 672
Author(s):  
Masahiro Funahashi
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Field Effect Transistors ◽  
Photovoltaic Effect ◽  
Electronic Charge ◽  
Circularly Polarized ◽  
Smectic C ◽  
Chiral Nematic ◽  
Crystal Phases ◽  
Liquid Crystal Phases

Liquid crystals bearing extended π-conjugated units function as organic semiconductors and liquid crystalline semiconductors have been studied for their applications in light-emitting diodes, field-effect transistors, and solar cells. However, studies on electronic functionalities in chiral liquid crystal phases have been limited so far. Electronic charge carrier transport has been confirmed in chiral nematic and chiral smectic C phases. In the chiral nematic phase, consisting of molecules bearing extended π-conjugated units, circularly polarized photoluminescence has been observed within the wavelength range of reflection band. Recently, circularly polarized electroluminescence has been confirmed from devices based on active layers of chiral conjugated polymers with twisted structures induced by the molecular chirality. The chiral smectic C phase of oligothiophene derivatives is ferroelectric and indicates a bulk photovoltaic effect, which is driven by spontaneous polarization. This bulk photovoltaic effect has also been observed in achiral polar liquid crystal phases in which extended π-conjugated units are properly assembled. In this manuscript, optical and electronic functions of these chiral π-conjugated liquid crystalline semiconductors are reviewed.

Theory of Circularly Polarized Light Emission from Chiral Nematic Liquid Crystalline Films

1996 ◽  
Vol 425 ◽  
Author(s):  
H. Shi ◽  
S. H. Chen
Keyword(s):  
Experimental Data ◽  
Film Thickness ◽  
Liquid Crystalline ◽  
Light Emission ◽  
Polarized Light ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Chiral Nematic ◽  
Polarized Emission ◽  
Crystalline Films

AbstractChiral nematic liquid crystalline films with fluorescent chromophores are capable of circularly polarized emission. A theory is presented in which the effects of anisotropic absorption and film thickness are accounted for. The predicted dissymmetry factor is compared with experimental data reported by Stegemeyer et al. and with the theory for the two limiting cases treated by Pollmann et al.

Oriental behaviour of some homologues of 4-n-pentyl-phenylthio-4′-n-alkoxybenzoate doped with dichroic dye

2008 ◽  
Vol 16 (3) ◽  
Author(s):  
D. Bauman ◽  
A. Zięba ◽  
E. Mykowska
Keyword(s):  
Liquid Crystal ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Orientational Order ◽  
Polarized Light ◽  
Emission Spectra ◽  
Smectic C ◽  
Fluorescence Measurements ◽  
Dichroic Dye ◽  
Linearly Polarized

AbstractThe long-range orientational order of three members of 4-n-pentylphenylthio-4′-n-alkoxybenzoate $$ (\bar nS5) $$ series doped with a dichroic dye was studied by means of electronic absorption and fluorescence measurements. The order parameters <P2> and <P4> as well as the orientational distribution function were determined on the basis of absorption and emission spectra of linearly polarized light recorded as a function of temperature in the nematic, smectic A, and smectic C phases. An influence of the dye molecular structure on the orientational order of the dye/liquid crystal mixture was observed. Moreover, the dependence of the order parameter values on the length of the alkoxy chain in liquid crystal molecules was found. It was shown that the order parameter <P4>, obtained from fluorescence measurements, can be helpful in recognizing the second-order or weakly first-order transitions between various liquid crystalline phases.

Vitrified Chiral−Nematic Liquid Crystalline Films for Selective Reflection and Circular Polarization

1999 ◽  
Vol 11 (6) ◽  
pp. 1590-1596 ◽  
Author(s):  
Dimitris Katsis ◽  
Philip H. M. Chen ◽  
John C. Mastrangelo ◽  
Shaw H. Chen ◽  
Thomas N. Blanton
Keyword(s):  
Circular Polarization ◽  
Liquid Crystalline ◽  
Selective Reflection ◽  
Chiral Nematic ◽  
Crystalline Films

scholarly journals Sequentially amplified circularly polarized ultraviolet luminescence for enantioselective photopolymerization

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Dongxue Han ◽  
Xuefeng Yang ◽  
Jianlei Han ◽  
Jin Zhou ◽  
Tifeng Jiao ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Uv Light ◽  
Upconversion Emission ◽  
Delayed Fluorescence ◽  
Circularly Polarized ◽  
Thermally Activated ◽  
Chiral Nematic ◽  
Circularly Polarized Luminescence ◽  
Further Development

Abstract Chiral optical materials based on circularly polarized luminescence (CPL) have emerged rapidly due to their feasible applications in diverse fields of research. However, limited to the small luminescence dissymmetry factor (glum), real application examples have rarely been reported. Here, we present a complex system, which show intense circularly polarized ultraviolet luminescence (CPUVL) with large glum value, enabling a chiral UV light triggered enantioselective polymerization. By integrating sensitized triplet-triplet annihilation upconversion and CPL, both visible-to-UV upconversion emission and upconverted circularly polarized ultraviolet luminescence (UC-CPUVL) were obtained in the systems, built of chiral annihilator R(S)-4,12-biphenyl[2,2]paracyclophane (R-/S-TP), and a thermally activated delayed fluorescence (TADF) sensitizer. After dispersing this upconversion system into room-temperature nematic liquid crystal, induced chiral nematic liquid crystal could significantly amplify the glum value (0.19) of UC-CPUVL. Further, the UC-CPUVL emission has been used to trigger the enantioselective photopolymerization of diacetylene. This work paves the way for the further development of functional application of CPL active materials.

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