[en] We studied an enhancement effect of defect fluorescence of ZnSe quantum dots (QDs) on a heterojunction of ZnSe QDs and gold nanoparticles. The photoluminescence (PL) of Au/ZnSe heterojunction is excited by using a 150 nm diameter ultraviolet laser spot of a scanning near-field optical microscope. Owing to the charge transfer of photon-generated carriers from ZnSe QDs, the enhanced PL effect is observed, which results from the increase of the built-in electric field to hinder the electron transfer to gold nanoparticles and is trapped by the defect states of ZnSe QDs. The broadening of defect fluorescence spectra and the reduction of excitonic fluorescence in multi-heterojunction of ZnSe QDs and gold nanoparticles are also observed which is attributed to an increase of their contact areas. We believe that enhanced defect fluorescence method described in this paper have potential applications in forming uniform optoelectronic heterojunction in controlling and boosting fluorescent efficiency of weak PL devices. (paper)

[en] This work studied the effect of differential temperatures on the latent heat in the nucleation of CdSe quantum dots (QDs). The result showed that, by the formula of phase change, with increasing the reaction temperature, the latent heat in the nucleation of QDs reduced. CdSe QDs with the size-dispersion from 2.7 to 3.6 nm were synthesized via oleic acid-paraffin liquid system by controlling the reaction temperature from 180 to 220 °C. Synthesized QDs were characterized by UV–vis absorption spectra and X-ray diffraction (XRD). The result of UV–vis absorption spectra showed that with increasing of reaction temperature, the first absorption peak was red-shifted and the size of QD increased. The result of XRD showed that the synthesized QDs were zinc-blende structure. (paper)

[en] We present the enhanced photoluminescence (PL) of a corrugated Al₂O₃ film enabled by colloidal CdSe quantum dots. The colloidal CdSe quantum dots are fabricated directly on a corrugated Al₂O₃ substrate using an electrochemical deposition (ECD) method in a microfluidic system. The photoluminescence is excited by using a 150 nm diameter ultraviolet laser spot of a scanning near-field optical microscope. Owing to the electron transfer from the conduction band of the CdSe quantum dots to that of Al₂O₃, the enhanced photoluminescence effect is observed, which results from the increase in the recombination rate of electrons and holes on the Al₂O₃ surface and the reduction in the fluorescence of the CdSe quantum dots. A periodically-fluctuating fluorescent spectrum was exhibited because of the periodical wire-like corrugated Al₂O₃ surface serving as an optical grating. The spectral topographic map around the fluorescence peak from the Al₂O₃ areas covered with CdSe quantum dots was unique and attributed to the uniform deposition of CdSe QDs on the corrugated Al₂O₃ surface. We believe that the microfluidic ECD system and the surface enhanced fluorescence method described in this paper have potential applications in forming uniform optoelectronic films of colloidal quantum dots with controllable QD spacing and in boosting the fluorescent efficiency of weak PL devices. (paper)