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Graphical abstract Highlights • The electron transfer dynamics of TCPP with different central metal ions adsorbed on ZnO nanorods have been studied. • Metalloporphyrins are formed by the metallation of porphyrin rings. • There is 4.5 times fold increase in efficiency for ZnO-TCPPM device as compare to device composed of free base porphyrin. Abstract The electron transfer dynamics of tetra(4-carboxyphenyl)porphyrin with different central metal ions Fe(III), Cu(II), Co(II),Ni(II), Zn(II) adsorbed on ZnO nanorods have been investigated by using photophysical and electrochemical studies. Spectroscopic studies confirmed that metalloporphyrins anchored onto ZnO through the carboxylic group. XPS studies indicated that replacement of free base porphyrin with different metals resulted in change in symmetry with uniform distribution of electron density of nitrogen atom of pyrrole ring which gives one broad peak of N1S state. Absorption studies revealed the bathochromic shift of soret band in ZnO-TCPPM nanocomposites as compare to free base porphyrin and metalloporphyrins owing to the electronic coupling between ZnO and TCPPM which stabilize the π* orbital. The photoluminescence properties of metalloporphyrins are shown to be highly dependent on central metal atom. Steady state and PL lifetime measurements studies shows the electron transfer in ZnO-TCPPM occurred feasibly for TCPPZn sensitizer as Zn(II)porphyrin have long lived excited state as compare to other metalloporphyrins. Improved photovoltaic properties of the metalloporphyrins are originated from electron injection driving force from dye to ZnO. Introduction of metal in porphyrin cavity increase the electron transfer process. Incase of TCPPCo, TCPPNi fast recombination exists between metal cation and photogenerated electron that inhibits the photocurrent generation. J–V Characteristics revealed there is 4.5 fold increases in efficiency for ZnO-TCPPM device as compare to device composed of free base porphyrin. [ABSTRACT FROM AUTHOR]

The optoelectronic properties of P3HT–CdSe nanocomposites prepared by insitu chemical oxidative polymerization were studied. CdSe QDs were synthesized by hot injection method using tri octyl phosphine oxide (TOPO) as capping ligand whereas the P3HT polymer was prepared by chemical oxidative polymerization. FTIR studies confirmed the regioregularity of the P3HT and revealed the chemical interaction of P3HT and CdSe in nanocomposite. Absorption studies showed blue shift for the nanocomposites as compare to pristine P3HT, the electron transfer from conducting polymer to the CdSe was detected by the measurements of quenching of photoluminescence from conducting polymer after the addition of semiconductor nano crystals which confirmed that an optimum amount of nanoparticles provide networking in hybrid composites. The optimal result for device prepared by P3HT–CdSe nanocomposites was open circuit voltage ( V oc ) 0.5, short circuit current density ( J sc ) 0.66, Fill factor (FF) 0.6855 and efficiency ( η ) 0.22%. [ABSTRACT FROM AUTHOR]

The present article reports the synthesis of three Eu(III) complexes [Eu(BA) 3 (2-ap)] ( 1 ), [Eu(HBA) 3 (2-ap)] ( 2 ) and [Eu(ABA) 3 (2-ap)] ( 3 ) (BA = benzoic acid, HBA = 2-hydroxy benzoic acid, ABA = 2-amino benzoic acid and 2-ap = 2-aminopyridine) carried out in ethanol solution. The complexes were further doped with CaF 2 nanoparticles and a change in the photoluminescence properties was observed. The compositions and structural investigation of the complexes were determined by elemental analysis and Fourier transform infrared spectroscopy (FTIR) which suggest the coordination of ligands with the central Eu(III) ion. The optical properties of the complexes were studied by Ultraviolet Visible absorption spectroscopy (UV–Vis) and photoluminescence studies (PL). The relative PL intensity was enhanced in the Eu(III) complexes doped with CaF 2 nanoparticles as compared to the pure Eu(III) complexes, however the increase in intensity varied in the order of ligands ABA > HBA > BA. The photoluminescence lifetime decay curves also revealed the longer lifetime ( τ ) and higher quantum efficiency ( η ) for europium complexes with ABA ligands suggesting the efficient energy transfer and better sensitizing ability of the ligand to europium ion. The morphology of the synthesized compounds were studied by Scanning Electron Microscopy (SEM) revealing spherical morphology with agglomeration of the nanoparticles. [ABSTRACT FROM AUTHOR]

Three europium complexes [Eu(2-ap) 3 (phen)]Cl 3 (1), [Eu(2-ap) 2 (phen) 2 ]Cl 3 (2) and [Eu(2-ap)(phen) 3 ]Cl 3 (3) have been synthesized with different molar ratios of ligands 2-ap and phen (where 2-ap is 2-aminopyridine, phen is 1,10-phenanthroline). The structures of the ligands and complexes were well characterized by elemental analysis, Fourier transform infrared spectroscopy (FT-IR) and powder X-ray diffraction studies (XRD). The optical properties of the complexes were investigated by ultraviolet visible absorption spectroscopy (UV-vis) and photoluminescence emission spectroscopy (PL) and photoluminescence lifetime decay measurements. The complexes exhibited intense red emission at 615 nm due to 5 D 0 → 7 F 2 transitions of the central Eu(III) ion. It was also observed that with increase in the molar ratio of ligand phen, the relative emission intensity of 5 D 0 → 7 F 2 transition at 615 nm was enhanced in complex (3) than in the complex (1) and complex (2), indicating that the complex (3) exhibited good luminescent properties. Furthermore, the complex (3) shows good quantum yield and long luminescence lifetime, hence it can be used as an efficient fluoroprobe. The thermal properties of the obtained complexes were studied by thermogravimetry analysis (TG-DTA) demonstrating the corresponding mass losses due to the ligands 2-ap and phen and the formation of stable oxide Eu 2 O 3 as the final product after decomposition. The morphologies as studied by Scanning Electron Microscopy (SEM) depicted different microstructures for all the three complexes revealing that the change in concentration of ligands leads to the change in morphologies of the complexes. [ABSTRACT FROM AUTHOR]

Nd3+/Yb3+ co-doped NaGdF 4 @CaF 2 :Eu3+ nanoparticles were prepared through oleic acid/1-octadecene based coprecipitation method. Their structural characterizations were carried out by using powdered XRD pattern, SEM and TEM studies. The synthesized nanoparticles showed dual-mode emission i.e., visible and NIR emission and thus displayed a broad range of photoluminescence emission covering a visible red emission (618 ​nm) to near infrared first/second window emission (900, 990, 1062 and 1340 ​nm). Photoluminescence spectral studies showed highest emission intensity for NaGdF 4 :0.1Nd3+,0.03Yb3+@CaF 2 :Eu3+. The color coordinates (x, y) for the visible emission of synthesized nanoparticles were calculated and the proposed energy transfer mechanism for NaGdF 4 :0.1Nd3+,xYb3+@CaF 2 :Eu3+ nanoparticles was explained. Image 1 • NaGdF 4 :Nd3+/Yb3+@CaF 2 : Eu3+ nanoparticles were synthesized by oleic acid/1-octadecence based coprecipitation method. • XRD, SEM and TEM results indicated that the synthesized nanoparticles are of cubic structure. • The nanoparticles exhibited dual kind of emission (NIR and visible) upon excitation at 800 nm and 395 nm respectively. • As a result of dual-mode emission, these nanoparticles can be employed in tunable lasers. [ABSTRACT FROM AUTHOR]