The performance of P3HT：PCBM solar cells was improved by anode modification using spin-coated Tb（aca）3phen ultrathin films. The modification of the Tb（aca）3phen ultrathin film between the indium tin oxide （ITO） anode and the PEDOT：PSS layer resulted in a maximum power conversion efficiency （PCE） of 2.99% compared to 2.66% for the reference device, which was due to the increase in the short-circuit current density （Jsc）. The PCE improvement could be attributed to the short-wavelength energy utilization and the optimized morphology of the active layers. Tb（aca）3phen with its strong down-conversion luminescence properties is suitable for the P3HT：PCBM blend active layer, and the absorption region of the ternary blend films is extended into the near ultraviolet region. Furthermore, the crystallization and the surface morphol- ogy of P3HT：PCBM films were improved with the Tb（aca）3phen ultrathin film. The ultraviolent-visible absorption spectra, atomic force microscope （AFM）, and X-ray diffraction （XRD） of the films were investigated. Both anode modification and short-wavelength energy utilization using Tb（aca）3phen in P3HT：PCBM solar cells led to about a 12% PCE increase.
The influence of channel length on the performances of carbon nanotube field effect transistors(CNT-FETs) has been studied.Buffered oxide etching was used to remove approximately a 60 nm layer from the original 100 nm silicon dioxide layer,to thin the dielectric layer of the back gate.Channel length of the CNT-FETs was changed along with the etching process.The dependence of drain-source current on gate voltage was measured to analyze the performance of the CNT-FETs,including the transconductance,carrier mobility,current ON/OFF ratio,etc.The results indicate that the devices still keep good quality.
FENG Ying,HUANG ShiHua,KANG Kai & FENG YuGuang Institute of Optoelectronic Technology,Beijing Jiaotong University,Beijing 100044,China
Photostimulated luminescence(PSL) is observed in BaBrCl:Eu2+ after X-ray irradiation at room temperature.It is suggested by PSL stimulation spectrum and difference absorption spectrum(DAS) that F centers are formed upon X-ray irradiation and both spectra show two bands which are centered at about 550 nm and 675 nm respectively.This enables the use of semiconductor light-emitting diodes(LED) instead of gas lasers for photostimulation.The PSL intensity increases linearly with X-ray irradiation dose increasing,and the conversion efficiency is 29% that for the standard commercial storage phosphor BaFBr:Eu from Fuji imaging plate.
