The films of two x-shape oligo（thiophene）s, 3, 4-dibithienyl-2, 5-dithienylthiophene （7T） and 2, 5-dibithienyl-3, 4- ditrithienylthiophene （11T）, which are prepared by vacuum evaporation, have been investigated as novel electron donor layers in two-layer photovoltaic cells. UV-Vis absorptions show red-shifted and broadened absorptions of the vacuumevaporated films as compared with those of the corresponding solutions and spin-coating films, which is beneficial for photovoltaic properties. X-ray diffraction （XRD） and differential scanning calorimetry （DSC） measurements show that the vacuum-evaporated films are almost amorphous. Two-layer photovoltaic cells have been realized by the thermal evaporation of 7T and llT as donors and N, N′-bis（1-ethylpropyl）-3, 4：9,10-perylene bis（tetracarboxyl diimide） （EP- PTC） as an acceptor. An energy conversion efficiency （ECE） of 0.18% of the cell based on 7T with an irradiation of white light at 100 mw/cm^2 has been demonstrated by the measurements of current （I）- voltage （V） curves of the cells to be higher than the ECE of the reference system based on donor dihexylterthienyl （H3T） that is linear and without α, β linkage.
White organic light-emitting diodes with a blue emitting material fluorene-centred ethylene-liked carbazole oligomer （Cz6F） doped into polyvinyl carbazole （PVK） as the single light-emitting layer are reported. The optical properties of Cz6F, PVK, and PVK：Cz6F blends are studied. Single and double layer devices are fabri- cated by using PVK： Cz6F blends, and the device with the configuration of indium tin oxide （ITO）/PVK：Cz6F/ tris（8-hydroxyquinolinate）aluminium （Alq3）/LiF/A1 exhibits white light emission with Commission Internationale de l＇Eclairage chromaticity coordinates of （0.30, 0.33） and a brightness of 402 cd/m^2. The investigation reveals that the white light is composed of a blue-green emission originating from the excimer of Cz6F molecules and a red emission from an electroplex from the PVK：Cz6F blend films.
