Mn掺杂ZnSe量子点变温发光性质研究

量子点(QD)照明器件中电流导致的焦耳热会使其工作温度高于室温,因此研究量子点的发光热稳定性十分重要。本文利用稳态光谱和时间分辨光谱研究了具有不同壳层厚度的Mn掺杂ZnSe(Mn: ZnSe)量子点的变温发光性质,温度范围是80～500 K。实验结果表明,厚壳层(6.5单层(MLs))Mn: ZnSe量子点的发光热稳定性要优于薄壳层(2.6 MLs)的量子点。从80 K升温到400 K的过程中,厚壳层Mn: ZnSe量子点的发光几乎没有发生热猝灭,发光量子效率在400 K高温下依然可以达到60%。通过对比Mn: ZnSe量子点的变温发光强度与荧光寿命,对Mn: ZnSe量子点发光热猝灭机制进行了讨论。最后,为了研究Mn: ZnSe量子点的发光热猝灭是否为本征猝灭,对具有不同壳层厚度的Mn: ZnSe量子点进行了加热-冷却循环(300-500-300 K)测试,发现厚壳层的Mn: ZnSe量子点的发光在循环中基本可逆。因此,Mn: ZnSe量子点可以适用于照明器件,即使器件中会出现不可避免的较强热效应。

Temperature-dependent photoluminescence properties of Mn-doped ZnSe quantum dots

Thermal stability of quantum dot(QD) luminescence is considered as an important factor for their applications in luminescent devices because of the Joule heat caused by inevitable current. The temperature-dependent photoluminescence(PL) properties of Mn-doped ZnSe(Mn: ZnSe) QDs with different shell thickness in the temperature range from 80 to 500 K were studied by steady-state and time-resolved PL spectra. It was found that the Mn: ZnSe QDs with thick shell(6.5 monolayers(MLs)) exhibited better PL thermal stability than the thin shell coated ones(2.6 MLs). Because almost no PL quenching occurred for thick shell-coated Mn-doped QDs from 80 to 400 K, their PL quantum yield(QY) could keep 60% even at 400 K. Moreover, based on the change in temperature-dependent PL intensities and lifetimes of Mn: ZnSe QDs, the thermal quenching mechanism was proposed. Finally, the stability of Mn: ZnSe QDs with different shell thickness are discussed on the basis of heating-cooling cycling examination(300-500-300 K). For Mn: ZnSe QDs with thick shell, the PL was nearly totally recovered after the cycling examination. Thus, Mn: ZnSe QDs are promising for applications in luminescent devices, where strong thermal effect is inevitable.