Caution for monitoring the surface modification of dually emitted ZnSe quantum dots by time-resolved photoluminescence

This work wants to give a caution for monitoring the surface modification of dually emitted ZnSe quantum dots (QDs) by using time-resolved photoluminescence (PL). Aqueous ZnSe QDs have two emission bands: namely ZnSe band gap emission centered at 395 nm and ZnSe trap emission centered at 470 nm. By fitting the measured PL spectra by two peaks, serious overlapping of two emission bands can be found in the range of 360?430 nm. As a result, the measured PL lifetimes at 395 nm (the peak position of ZnSe band gap emission) is just an apparent value, composing of both ZnSe band emission (contribution proportion about 80%) and ZnSe trap emission (contribution proportion about 20%). Due to the much smaller PL lifetime of ZnSe band gap emission (less than 20 ns) than that of ZnSe trap emission (about 50?70 ns), the elevated contribution proportion of ZnSe band gap emission at improved QD surface modification will lead to the decreased average PL lifetime at 395 nm. This result is complete...

Chunlei Wang, Zhiyang Hu, Shuhong Xu, Shujie Zhou, Zhuyuan Wang and Yiping Cui

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