The different compositions of the ternary alloyed CdSe_(x)S_(1-x)quantum dots(QDs)and CdSe_(x)S_(1-x)/ZnS core/shell quantum dots(CSQDs)have been synthesized by the chemical routes.The radii of these QDs were determined by transmission electron microscope(TEM).The optical properties of these QDs were investigated by the absorption and fluorescent measurement.It was found that the absorption and fluorescent emissions were tuned by the component ratio,and the Commission Internationale de l´Eclairage(CIE)coordinates of the fluorescent spectra also depended on the composition.Compared with the CdSe_(x)S_(1-x)QDs,the CdSe_(x)S_(1-x)/ZnS CSQDs exhibit the fluorescence enhancement due to the surface passivation by shell coating.The composition-tuned optical properties may allow them to be used as fluorescent markers in biological imaging and to fabricate multicolor light emitting diode(LED).
The nonlinear optical properties of P3HT in orthodichlorobenzene were investigated by Z-scan technique using second harmonic generation(532 nm) of mode-locked Nd:YAG laser in the picosecond domain. The experimental results show the magnitude of their nonlinear refraction indices was up to the order of 10^(-11) esu. The reverse saturable absorption of P3HT solution was observed and their nonlinear absorption coefficients reach up to 3.4 cm/GW. The strong optical nonlinearity of P3HT may find its new application in the photoclectric field.
The pentacene-based organic field effect transistor （OFET） with a thin transition metal oxide （WO3） layer between pentacene and metal （AI） source/drain electrodes was fabricated. Compared with conventional OFET with only metal AI source/drain electrodes, the introduction of the WO3 buffer layer leads to the device performance enhancement. The effective field-effect mobility and threshold voltage are improved to 1.90 em2/（V.s） and 13 V, respectively. The performance improvements are attributed to the decrease of the interface energy barrier and the contact resistance. The results indicate that it is an effective approach to improve the OFET performance by using a WO3 buffer layer.
