Photovoltaic properties of photodiodes based on nano-TiO_2 and poly[2-methoxy,5-(2′-ethlhexyloxy)- p-phenylenevinylene] (MEH-PPV) composites are investigated. By comparing composite devices with the same weight of TiO_2 (nanoparticles and nanotubes):MEH-PPV, it was found that the device with TiO_2 nanotubes exhibited better performance. By further optimizing the weight radio of TiO_2 nano- tubes:MEH-PPV, we gained the device with a short circuit current density of 9.27 μA/cm2 with a light intensity of 16.7 mW/cm2 at the 500 nm wavelength, the highest open-circuit voltage of 1.1 V, and a photosensitivity of 332 at reverse bias of -0.6 V. The photosensitivity is improved by a factor of 33 compared with the undoped MEH-PPV device.
LI Yan HOU YanBing JIN Hui SHI QuanMin WANG Yan FENG ZhiHui
The carrier transport properties of the blends of the hole transport material poly(N-vinylcarbazole) (PVK) and the electron transport material tris (8-hydroxyquinolinolato) aluminumⅢ(Alq_3) are investigated at room temperature using steady-state and time-resolved transient photocurrent measurements as a function of doping concentration of Alq_3.Due to lower LUMO and higher HOMO energy level of Alq_3 than those of PVK,Alq_3 molecules may act as carrier trap states in PVK films at low concentration.However,at...
CdSe nanocrystals were prepared by a colloidal chemical approach using CdO and Se powder as precursors in an organic system of TOPO/TOP, and a multilayered electroluminescence device was fabricated with CdSe as emitting layer. The results show that the photoluminescence spectra of the CdSe nanocrystals almost cover the whole visible region and the full width at half maximum （FWHM） is appropriately 200 nm. The electroluminescence spectrum of the multilayered device at different voltages was investigated. The electroluminescence intensity is enhanced with increasing operating voltage, and the CIE coordinates of the device change from （0.3,0.37） at 6 V to （0. 44,0. 46）at 20 V as the operating voltage increases,which indicates that the colors of the device could be tuned by the operatina voltage.
TANG Ai-wei TENG Feng GAO Yin-hao LI Dan LIANG Chun-jun WANG Yong-sheng
