Three terbium complexes Tb (tba-PMP) 3 (TPPO) (A), Tb (tba-PMP) 3 (H2O) (B), and Tb (tba-PMP) 3 (Phen) (C) (where tba-PMP, TPPO, and Phen stand for diketone 1-phenyl-3-methyl-4-(tert-butylacetyl)-5-pyrazolone, triphenyl phosphine oxide, and 1, 10-phenanthroline, respectively) with different neutral ligands were synthesized and characterized, and the mechanism of how the neutral ligands affect photoluminescence (PL) and electroluminescence (EL) properties of terbium complexes was studied. Experiments revealed neutral ligand TPPO and Phen strongly affect the terbium complex PL intensity, TPPO enhanced the PL intensity of complex A, while Phen reduced the PL intensity of complex C compared to that of complex B. Investigation indicated this is caused by the different excited energy levels between tba-PMP, TPPO, and Phen, which were obtained from their phosphorescence spectra measured with their corresponding gadolinium complexes Gd(tba-PMP)3-(H2O)(EtOH), Gd (TPPO) 2 (NO3) 3, and Gd (Phen) 2 (NO3) 3. Compared to complex B, the energy absorbed by TPPO can be efficiently transferred to tba-PMP and the central ion Tb3+ due to its excited singlet and triplet energy levels matching that of tba-PMP and the 5D4 energy level of Tb3+, and consequently enhancing the PL intensity of A, while on the contrary, negative energy transfer occurred between Phen and tab-PMP or Tb3+ since the triplet energy level of Phen is lower than that of tba-PMP and the 5D4 energy level of Tb3+ as well. Experimental results show terbium complex electroluminescence (EL) is greatly dependent on its PL intensity, the performance achieved based on complexes A, B, and C being 9540 cd/m2 and 7.2 lm/W, 3230 cd/m2 and 1.17 lm/W, and 690 cd/m2 and 0.13lm/W, respectively, with the power efficiency ratio A:B:C)55:9:1, which was greatly enlarged compared to their PL intensity ratio A:B:C) 2.1:1.3:1.

The absorption of a nanoporous TiO2 thin film was enhanced throughout the visible wavelengths with surface modification of Sr2+, especially in the range of shorter wavelengths. Charge separation efficiency from laser experiment was measured. Data show that the incident photon to current efficiency of a solar cell based on the dye Ru [LL

A series of hemicyanine dyes, including monomer ([(E)-N-methyl-4-(2-(4-N, N-dimethyl phenyl) ethenyl) pyridinium] iodide; M) and dimers (1, n-Bis [(E)- 4-(2-(4-N, N-dimethyl phenyl) ethenyl) pyridinyl]-alkane dibromide; n) 3, alkane) propane, B3; n) 5, alkane) pentane, B5; n) 12, alkane) dodecane, B12), are synthesized and their ultrafast fluorescence up-conversion behaviors are studied. The fluorescence decay curves of these dyes can be well fitted by the sum of several exponential decays in the shorter wavelengths and by the sum of the exponential rise(s) with decay(s) in the longer wavelengths. The fact that the values of longest lifetime component at longer wavelengths tend to be a constant proves the existence of a "sink" region on the potential energy surface of excited state. This sink region is around the TICT state, by which the nonradiative transition dominates the deactive decay paths of excited state. The time dependent Stokes shift function analysis of these four dye molecules in methanol indicates that the B5's unique "solvation" behavior is different from others. This difference is contributed by the increased difficulty of the TICT formation of B5 originated from its folded conformation. The time dependent Stokes shifts of M, B3, and B12 are due to not only solvation dynamics but also TICT formation. Detailed analysis is presented in the frame of a "two-state three-mode" model.

A series of hemicyanine dimers, (B3, B5, and B12) whose two chromophores are linked by different numbers of methylene groups, are synthesized. Negative slovatochromic behaviors are observed, and the fluorescence quantum yield is sensitive to the polarity of solvent. In chloroform, the fluorescence intensity is much more intensive than in other polar solvents, and the decay lifetime is much longer. This fluorescence sensitivity to solvent is due to the twisted intramolecular charge transfer (TICT) state formation, which can be blocked in weak polar solvent. The two chromophores in one dimer molecule are correlated and the TICT formation of dimer is relatively difficult compared with monomer. When the linkage is long enough, this correlation can be reduced. The dynamic fluorescence spectra of the chloroform solutions of these dyes support our assumption. The time-resolved fluorescence studies of their LB films provide a new perspective on the excited-state deactive process. The two-dimensional Fo