Enhanced photoluminescence of corrugated AlO film assisted by colloidal CdSe quantum dots.

We present the enhanced photoluminescence (PL) of a corrugated AlO film enabled by colloidal CdSe quantum dots. The colloidal CdSe quantum dots are fabricated directly on a corrugated AlO 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 AlO, the enhanced photoluminescence effect is observed, which results from the increase in the recombination rate of electrons and holes on the AlO 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 AlO surface serving as an optical grating. The spectral topographic map around the fluorescence peak from the AlO areas covered with CdSe quantum dots was unique and attributed to the uniform deposition of CdSe QDs on the corrugated AlO 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.