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Various compositional photovoltaic cells based on the blend of poly(3-hexylthiophene) (P3HT) as donors and TiO2 nanocrystals as acceptors are fabricated and investigated. It is demonstrated that the blend ratio of P3HT and TiO2 nanocrystals could greatly influence the performance of the photovoltaic cells. The maximum of 0.411% in power conversion efficiency under AM 1.5, 100mW/cm2, and 44.4% of fill factor are obtained in the solar cell with the blend weight ratio 1:1 of P3HT and TiO2 nanocrystals. The function of nanocrystal composition is discussed in terms of the results of photoluminescence spectroscopy, atomic force microscopy, transmission electron microscopy, and charge transport I–V curve.

Polymer photovoltaic devices based on poly(3-hexylthiophene) (P3HT) : [6,6]-phenyl-C61-butyricacid methyl ester (PCBM) 1:1 weight-ratio blend are reported. The effects of various annealing treatments on the device performance are investigated. Thermal annealing shows significant improvement of the device performances. For devices at 130°C annealing, maximum power conversion efficiency (PCE) of 3.3% and fill factor up to 60.3% is achieved under air mass 1.5, 100 mW/cm2 illumination. We discuss the effect of thermal annealing by the results of ultraviolet-visible absorption spectroscopy (UV-vis), dark current-voltage curve, atomic force microscopy (AFM).

Polymer white-light-emitting diodes are fabricated based on the blend of poly[9,9-di-(2-ethylhexyl)-fluorenyl-2,7-diyl]-end capped with polysilsesquioxane (PFO) and a chelating copolymer ofpoly[(9,9-bis(3'-(N,N-dimethylamino) propyl)-2,7-fluorene-alt-2,7-(9,9-dioctylfluorene))-co- [2,7-(9,9-dioctlyfluorene)-alt-5,5-bis(2-(4-methyl-1-naphtha-lene) pyridine-C2,N) iridium (III) acethylacetonate]] (PFN-NaIr). The device with the sole aluminium cathode is able to produce a comparably white electroluminescence efficiency of 1.31 cd/A to that of the device using low work function cathodes (such as Ba, Ca, etc.). The CIE coordinates of the white light emission consisting of red, green and blue three components are nearly at (0.34, 0.35). The mechanism of the white light emission from the device with the Al cathode is investigated, which is related to the efficient injection of electrons through the interface of PFN-NaIr/Al.

We demonstrate a high efficiency top-emitting polymer light-emitting diode (TPLED) with chromium (Cr) taking as the anode. The TPLED structure is Cr/poly-3, 4-ethylenedioxythiophene (PEDOT:PSS)/poly [2-(4-3',7'-dimethyloctyloxy)-phenyl]-p-phenylenevinylene) (P-PPV)/Ba/Ag. The Cr (100 nm) anode is prepared by sputter-depositing in a vacuum chamber. It is found that the device emissive properties are affected dramatically by the thickness of both PEDOT:PSS and the Ag cathode. Optimized thicknesses of PEDOT:PSS and Ag layer are 60 nm and 15 nm, respectively. The diode exhibits excellent electroluminescence (EL) properties, such as a turn-on voltage of 3.32 V, luminous efficiency of 4.41 cd/A and luminance of 6989 cd/m2 at driving voltage of about 9 V.

We report on simultaneous magneto-optical trapping of fermionic 40K and bosonic 87Rb atoms. This trap is the first step towards quantum degenerate fermi gas 40K. Laser lights for the two-species magneto-optical trap (MOT) are generated from diode lasers and tapered amplifier. The enriched 40K dispenser is utilized in the experimental setup. We obtain up to 107~108 40K and 108~109 87Rb atoms respectively in the steady-state single-species MOT.

High-efficient saturated red light-emitting diodes are realized based on a bilayer of phenyl-substituted poly [p-phenylene vinylene] derivative (P-PPV) and copolymer (PFO-DBT15) of 9,9-dioctylfluorene (DOF) and 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DBT). External electroluminescent (EL) quantum efficiency of PFO-DBT15 is increased from 1.6% for a single-layer device to 4.7% for the bilayer device by insertion of a P-PPV layer between PEDOT (polyethylene dioxythiophene-polystyrene sulfonic acid) and PFO-DBT15 at the current density of 35 mA/cm2. The luminescence efficiency reaches 0.83 cd/A, and the Commission Internationale de I'Eclairage coordinates (CIE) become nearly x = 0.700 and y = 0.300. In comparison with the devices from PFO-DBT15 and P-PPV blend films, the P-PPV/PFO-DBT15 bilayer device shows higher EL quantum efficiency and better stability under high current density. The improved device performance can be attributed to the charge-confinement effect at the interface of the P-PPV/PFO-DBT15 bilayer structure.

The electroluminescent characteristics of polymer light-emitting diodes (PLEDs) with the structure ITO/PEDOT/ PFO-Selenophene copolymer/cathode were investigated. Various cathodes, such as Al, Li/Al, Ba/Al, LiF/Al and LiF/Ba/Al, were used for testing the device performances. The strongest light output (1112 cd/m2) and the highest quantum efficiency (0.74%) were achieved by using the LiF/Ba/Al cathode. A possible working mechanism for improving the PLED performance was discussed.

The enhancement of electroluminescent (EL) performance of polymer light emitting diodes (PLEDs) with electron transport emitter poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) through thermal annealing treatment is investigated. Post-annealing of the PLEDs at temperature 120°C over the glass transition temperature of F8BT (99°C) could bring about an improvement of EL efficiency to more than twice that of the untreated devices, up to 6.02 cd/A. The improvement of the EL efficiency is due to the balance of electron and hole carriers in the exciton recombination zone, because the dominative electron current in the PLEDs could be reduced by post-annealing in terms of both issues of electron transport limited in the F8BT film and electron injection decreased by the interface between F8BT/cathode.

First-principles local density functional calculations are presented for the compounds ZnGa2X4 (X = S,Se). We investigate the bulk moduli and electronic band structures in a defect chalcopyrite structure. The lattice constants and internal parameters are optimized. The electronic structures are analysed with the help of total and partial density of states. The relation between the cohesive energy and the unit cell volume is obtained by fully relaxed structures. We derive the bulk modulus of ZnGa2X4 by fitting the Birch–Murnaghan's equation of state. The extended Cohen's empirical formula agrees well with our ab initio results.