Sensitized Luminescence of Rare Earths

The enhancement effect on the fluorescence intensities of an Eu3+ (or/and Sm3+ )-thenoyltrifluoroacetone (TTA )-dibenzo-18-crown-6 (18-C-6 ) system and Eu 3+ (or /and Sm3+ ) -benzoyltrifluoroacetone (BTA )-cetyltrimethylammonium bromide (CTMAB) system by dysprosium has been studied. In the presence of enhancing ions, the fluorescence intensities of the above systems were enhanced by a factor of about 40-150, respectively. The above systems were used for the determination of europlum or/and samarium in rare earths oxides and gave satisfactory results.

Efficient two-photon sensitized luminescence of europium (Ⅲ) complex based on hypersensitive transitions

Red frequency-upconversion fluorescence emission is observed in europium（Ⅲ） complex with encapsulating polybenzimidazole tripodal ligands, pumped with 930- and 1070-nm picosecond laser pulses. The lumines- cence of transition 5D0 →7F2 （612 nm） is induced by two-photon absorption of hypersensitive transitions 7F0 →5D2 （465 nm） and 7F1 →5D1 （535 nm）. Analysis results suggest that the two-photon excitation strength of these hypersensitive transitions is increased dramatically owing to the C3 symmetry of the coordination field.

Enhancement of sensitized photoluminescence of erbium chloride silicate through regulating annealing

Erbium chloride silicate(ECS)nanocrystals and Si nanocrystals(Si NCs)co-embedded in silica films were prepared.And the sensitized luminescence of ECS was realized through interparticle energy transfer(IPET)in solid matrix.We focus on the effect of annealing temperature on the film microstructure and sensitized luminescence.The samples annealed at 1100℃have a moderate level of energy transfer efficiency and total Er3+concentration capable of radiative recombination.At the same time,they also have high luminescence intensity of Si NCs.Therefore,the samples annealed at 1100℃have good sensitizing luminescence performance of ECS.The strong luminesce nce intensity of sensitizers Si NCs and adjacent crystalline ECS nanocrystals are the keys to achieve excellent IPET in the solid matrix.The results provide a basis for optimizing sensitized luminescence of erbium compounds by regulating annealing.

Luminescence and energy transfer of Ce^(3+)-Eu^(2+) in Ca_9Al(PO_4)_7

A series of Ce^(3+),Eu^(2+) and Ce^(3+)-Eu^(2+) doped Ca_9Al(PO_4)_7 phosphors are synthesized by a high temperature solid-state method.Under 291 nm excitation,Ca_9Al(PO_4)_7:Ce^(3+) has one emission band at 356 nm,which is attributed to4f°5d^1→4f^1 transition of Ce^(3+).Under 305 nm excitation,Ca_9Al(PO_4)_7:Eu^(2+) presents one emission band at 445 nm,which is assigned to 4f^65d^1→4f^7 transition of Eu^(2+).Energy transfer from Ce^(3+) to Eu^(2+) in Ca_9Al(PO_4)_7 is validated and proved to be a resonant type via a quadrupole-quadrupole interaction.Critical distance(R_c) of Ce^(3+) to Eu^(2+) in Ca_9Al(PO_4)_7 is calculated to be 1.264 nm.Moreover,the emission intensity of Ca_9Al(PO_4)_7:Ce^(3+),Eu^(2+) can be tuned by properly adjusting the relative doping composition of Ce^(3+)/Eu^(2+).

A new indium-based MOF as the highly stable luminescent ultra-sensitive antibiotic detector

A novel luminescent double-interpenetrated metal-organic framework(MOF),named{[In_(6)(O)_(3)(BTB)_(4)]·3H_(2)O}_(n)(1),is designed and synthesized using the tritopic linkers(1,3,5-tris(4-carboxyphenyl)benzene(H_(3)BTB))and tetranuclear clusters[In_(4)O_(2)(COO)_(8)].1 features 3,8-connected dual-wall"cage-in-cage"and exhibits excellent chemical stability owing to its high connectivity and double-interpenetrated architectures.Moreover,it could rapidly detect thiamphenicol(THI),nitrofurazone(NFZ),and nitrofurantoin(NFT)antibiotics in N,N-dime-thylformamide(DMF)with superior detection sensitivity(Ksv)and low detection limits(LOD)of 4.52×10^(3)M^(-1)and 348.6 ppm,1.43×10^(5)M^(-1)and 13.8 ppm,and 1.47×10^(5)M^(-1)and 12.1 ppm for THI,NFZ,and NFT,respectively.Additionally,compound 1 exhibits good selectivity and recyclability.It is also effectively used to detect NFT in the milk sample.Furthermore,the mechanism of luminescence quenching was revealed through the experimental results and the density functional theory calculations.The occurrence of photo-induced electron transfer(PET)affects the fluorescence quenching effect of NFT and NFZ.The design of indium-based MOFs has the potential to detect antibiotic residues in food.

Performance improvement of DBP-based solar cells by introducing a luminescent sensitizer bis[(4,6-difluorophenyl)-pyridinato-N,C^(2')]c(picolinate)iridium(III)(Flrpic)

In this work,a sky-blue luminescent down-shifting(LDS)layer bis[(4,6-difluorophenyl)-pyridinato-N,C^(2')]c(picolinate)iridium(II)(FIrpic)was inserted between tetraphenyl dibenzoperiflanthene(DBP)and Mo0_(3)as UV-screen and sensitizer for smallmolecule DBP/C_(60)based planar heterojunction(PHJ)solar cells.With 8-nm Flrpic theshort circuit current(J_(sc))and power conversion efficiency(PCE)of the device areenhanced by 28%and 15%,respectively,probably originating from the re-absorption ofthe photons emitted from Flrpic.The V_(oc)linearly increases over 1-nm Flrpic,ascribed tothe deeper HOMO level of Flrpic than DBP,while the fill factor continuously declines from 3-to 10-nm Flrpic.The EQE spectra prove that the J_(sc)is mainly contributed by thephotocurrent generated in DBP and C_(60)layers.When the FIrpic thickness is 8 nm,the filmsurface is very uniform with the smallest water contact angle.The impedance spectro-scopy demonstrates that the device resistance gradually increases from 4.1×10^(4)Ω(without Flrpic)to 4.6×10^(4)Ω(with 10-nm Flrpic)with the FIrpic thickness rise,simultaneously the device transits from the insulating state into the conductive statefaster for the thin Flrpic layer than the thick layer.