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 morphology 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.
