This paper investigates the effects of concentration on the crystalline structure, the morphology, and the charge carrier mobility of regioregular poly（3-hexylthiophene） （RR-P3HT） field-effect transistors （FETs）. The RR-P3HT FETs with RR-P3HT as an active layer with different concentrations of RR-P3HT solution from 0.5 wt% to 2 wt% are prepared. The results indicate that the performance of RR-P3HT FETs improves drastically with the increase of RR-P3HT weight percentages in chloroform solution due to the formation of more microcrystalline lamellae and bigger nanoscale islands. It finds that the field-effect mobility of RR-P3HT FET with 2 wt% can reach 5.78×10^-3 cm^2/Vs which is higher by a factor of 13 than that with 0.5 wt%. Further, an appropriate thermal annealing is adopted to improve the performance of RR-P3HT FETs. The field-effect mobility of RR-P3HT FETs increases drastically to 0.09 cm^2/Vs by thermal annealing at 150 ℃, and the value of on/off current ratio can reach 104.
A novel co-doped rare earth complex Gd0.5Eu0.5（TTA）3Dipy was synthesized and chosen as the emitter material in the organic electroluminescent device ITO/PVK：Gd0.5 Eu0.5 （TTA）3Dipy/PBD/A1. It was proved that there was Forster energy transfer from Gd^3＋ to Eu^3＋. The electroluminescent mechanism of the device was proposed by measuring and analyzing the emission and the excitation spectra of the emissive layer. Gd^3＋ might play the role of promoting the en- ergy transfer from PVK to Eu^3＋ and inhibiting an intrinsic luminescence of PVK. The device displayed red light with good monochromaticity. The possible energy transfer process of the device was preliminarily discussed.
