What question did this study set out to answer?

The research aims to analyze the excitation dynamics and fluorescence properties of liquid crystalline nanocomposites doped with europium and niobium oxide nanoparticles.

February 8, 2026Journal of Physics Condensed Matter0 citations

Tunable excitation dynamics, fluorescence decay and microstructural analysis of Eu2O3, Nb2O5 nanoparticles doped birefringent liquid crystals

SNSantosh Nandi VAVinayak Mahadev Adimule RKRangappa S. Keri

Key Points

The research aims to analyze the excitation dynamics and fluorescence properties of liquid crystalline nanocomposites doped with europium and niobium oxide nanoparticles.
Synthesize liquid crystalline nanocomposites (LCNCs) with azobenzene derivatives and nanoparticles of Eu2O3 and Nb2O5.
Characterize the structure and purity using powder X-ray diffraction and scanning electron microscopy.
Conduct optical studies, including photoluminescence and fluorescence decay measurements at various excitation wavelengths.
3a@Eu2O3 and 3b@Nb2O5 exhibit pronounced luminescence maxima across various colors under different excitations.
The quantum yield ranged from -0.0777% to 0.0523% for 3a@Eu2O3 and from 0.86% to 0.14% for 3b@Nb2O5 depending on excitation wavelength.
Room temperature photoluminescence studies indicated sharp emission peaks associated with vibrant colors.

Abstract

Abstract In this investigation, liquid crystalline nanocomposite (LCNCs) of azobenzene derivatives 3a (methyl 4- (E) - (4-butoxy-2, 5-difluorophenyl) diazenyl-3-methoxybenzoate), and 3b (methyl 4- (E) -2, 5-difluoro-4- (hexyloxy) phenyldiazenyl-3-methoxybenzoate) were doped with 0. 5wt. % europium oxide (Eu2O3), niobium oxide (Nb2O5) nanoparticles (NPs) and named as 3a@Eu2O3, 3b@Nb2O5 LCNCs. The powdered X-ray diffraction confirms the purity and integration of Eu2O3, Nb2O5 NPs. Field emission scanning electron microscope studies demonstrate a non-uniform worm/flake-like morphology with agglomeration of LCNCs. A slight shift in optical band gap was observed for 3a, 3b LCNCs, and broad absorption bands were observed in ultraviolet-visible studies. The existence of birefringent textures of 3a@Eu2O3 and 3b@Nb2O5 LCNCs is confirmed using a polarizing optical microscope. Room temperature photoluminescence (RTPL) studies demonstrate pronounced luminescence maxima with sharp emission peaks of violet, blue, green emissions under excitation at 380nm, 460nm, 360nm, and 375nm. Steady state photoluminescence (SSPL) of 3a@Eu2O3 LCNC exhibits luminescence maxima associated with vibrant red, blue, and greenish-yellow colors, while SSPL of 3b@Nb2O5 LCNC shows emission peaks of brilliant blue, yellow, green, orange, red colors at various λexcitations. Furthermore, the large Stokes shift and full width at half maximum of 3a@Eu2O3 and 3b@Nb2O5 LCNCs are attributed to the presence of additional/virtual energy levels during the photoexcitation process. The fluorescence decay studies of 3a@Eu2O3 LCNC display average lifetime dwell between 19. 8ns to 0. 276ns, while 3b@Nb2O5 exhibits 9. 69ns to 10. 20ns, at various excitation wavelengths. The quantum yield varies between ˗7. 77 ×10˗2% to 5. 23×10˗2% and 0. 86% to 0. 14% for 3a@Eu2O3 and 3b@Nb2O5 LCNCs, respectively, upon increase in λexcitations. Polarization studies of 3a@Eu2O3 LCNC at λexcitation/emission angle (0°) showed intense defect-centered blue, red emission bands (445nm, 613. 8nm) attributed to the excited state virtual orbitals that undergo non-radiative decay with higher energy content. Thus, the results obtained for synthesized 3a, 3b LCs doped with Eu2O3 and Nb2O5 NPs make these usable for advanced optoelectronics, photonic, fluorescence/photo-luminescence device applications.

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