Enhancing photoluminescent behavior of 2-(naphthalen-1-yl)-1,4,5-triphenyl-1H-imidazole by ZnO and Bi2O3

Fused Methoxynaphthyl Phenanthrimidazole Semiconductors as Functional Layer in High Efficient OLEDs

Efficient hole transport materials based on novel fused methoxynaphthyl phenanthrimidazole core structure were synthesised and characterized. Their device performances in phosphorescent organic light emitting diodes were investigated. The high thermal stability in combination with the reversible oxidation process made promising candidates as hole-transporting materials for organic light-emitting devices. Highly efficient Alq3-based organic light emitting devices have been developed using phenanthrimidazoles as functional layers between NPB [4,4-bis(N-(1-naphthyl)-N-phenylamino)biphenyl] and Alq3 [tris(8-hydroxyquinoline)aluminium] layers. Using the device of ITO/NPB/4/Alq3/LiF/Al, a maximum luminous efficiency of 5.99 cd A(-1) was obtained with a maximum brightness of 40,623 cd m(-2) and a power efficiency of 5.25 lm W(-1).

Structural, compositional and textural properties of monoclinic α-Bi₂O₃ nanocrystals

Perfect α-Bi2O3 nanocrystals were successfully synthesized via green synthesis method. X-ray diffraction studies clearly revealed a single phase α-Bi2O3 nanocrystal without any secondary phase. The strong XPS peaks observed at 160 and 165 eV were assigned to Bi4f5/2 and Bi4f7/2 and clearly revealed Bi(3+) valence states of bismuth ions. Photoluminescence spectra revealed the perfect α-Bi2O3 crystal nature without having inter band transitions between defects, impurity and different valence states of bismuth ions. Out of thirty expected modes, the symmetry assignments of Raman bands correlated to Bg(4), Ag(5), Bg(5), Bg(6), Ag(7), Ag(8), Ag(9), Ag(10), Ag(12) and Ag(14) modes revealed perfect α-Bi2O3 nanocrystals. Transmission electron microscopy studies combined with a selected area electron diffraction pattern recorded on α-Bi2O3 nanocrystals show monoclinic structure preferential orientation with sizes approximately 200 nm in diameters and 500 nm in length.

Donor-acceptor binding interaction of 1-(naphthalene-1-yl)-2,4,5-triphenyl-1H-imidazole with semiconductor nanomaterials

The dynamics of photoinduced electron injection from 1-(naphthalene-1-yl)-2,4,5-triphenyl-1H-imidazole (NTI) to pristine ZnO, Mn-doped TiO2 and BaTiO3 nanoparticles have been studied by absorption, fluorescence and lifetime spectroscopic methods. Both the absorption and fluorescence results suggest the association between the nanoparticles and NTI. The calculated free energy change (ΔGet) confirms the electron injection from NTI to nano semiconductors. The critical energy transfer distance between NTI and the nanoparticles have been deduced. The emission of NTI is enhanced by pristine ZnO and quenched by Mn-doped TiO2 and BaTiO3 nanoparticles which are likely due to change of LUMO and HOMO levels of NTI on its association with nano semiconductors. The strong adsorption of the NTI on the surface of ZnO nanocrystals is likely due to the chemical affinity of the nitrogen atom of the NTI to the zinc ion on the surface of nanocrystals. Electron injection from photoexcited NTI to the CB(S(∗)→S(+)+eCB(-)) is likely to be the reason for the fluorescence enhancement.

Turn-off of fluorescence of styryl phenanthrimidazole on doping ZnO nanoparticles with Ce(3+)

ZnO nanoparticles were doped with Ce(3+) by sol-gel synthesis and characterized by high-resolution scanning electron microscopy (HR-SEM), powder X-ray diffraction (XRD) and UV-visible diffuse reflectance (DRS) and photoluminescence (PL) spectroscopies. The dynamics of photoinduced electron injection from styryl phenanthrimidazole to Ce(3+)-doped ZnO nanoparticles has been studied by absorption, fluorescence and lifetime spectroscopic methods. Both the absorption and fluorescence quenching results suggest association between Ce(3+)-doped ZnO and the phenanthrimidazole. The free energy change (ΔGet) for electron injection has been calculated. The critical energy transfer distance between the phenanthrimidazole and Ce(3+)-doped ZnO nanoparticles has been deduced. In contrast to our earlier observation of enhancement of fluorescence of the phenanthrimidazole by ZnO nanoparticles, doping ZnO with Ce(3+) turns off its fluorescence. These findings provide a method to test the presence of Ce(3+) in ZnO nanocrystals.

Synthesis and optical properties of phenanthromidazole derivatives for organic electroluminescent devices

The external quantum efficiency roll-off may be due to triplet–triplet annihilation (TTA) and triplet–polaron annihilation (TPA).

Nano rutile TiO2 catalysed synthesis of (E)-4-(2-(1-(4-chlorophenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)vinyl)-N,N-dimethylaniline and its interaction with super paramagnetic nanoparticles

The synthesis of (E)-4-(2-(1-(4-chlorophenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)vinyl)-N,N-dimethylaniline (CPPIVI) has been carried out using TiO₂ (R) as catalyst under solvent free conditions and characterized by NMR spectral studies.

Styryl phenanthrimidazole-fluorescence switched on by core/shell BaTiO3/ZnO and Mn-doped TiO2/ZnO nanospheres and switched off by the core nanoparticles

Photoelectron transfer to core/shell Mn–TiO₂/ZnO and BaTiO₃/ZnO nanospheres. Enhanced absorbance because of binding with nanosemiconductors. Enhanced emission due to charge injection from the excited ligand to CB of ZnO.