Low-Threshold Amplified Spontaneous Emission in Blue Quantum Dots Enabled by Effectively Suppressing Auger Recombination,Advanced Optical Materials

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Low-Threshold Amplified Spontaneous Emission in Blue Quantum Dots Enabled by Effectively Suppressing Auger Recombination
Advanced Optical Materials ( IF 8.0 ) Pub Date : 2021-03-14 , DOI: 10.1002/adom.202100068
Sheng Wang ₁ , Jiahao Yu ₂ , Haiqiao Ye ₁ , Mingbo Chi ₃ , Heng Yang ₁ , Haihui Wang ₁ , Fan Cao ₁ , Wenqiang Li ₁ , Lingmei Kong ₁ , Lin Wang ₁ , Rui Chen ₂ , Xuyong Yang ₁

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The amplified spontaneous emissions in blue quantum dots (QDs) are still constrained by their high thresholds due to the challenge in engineering alloyed core–shell interface in the QDs with a wide bandgap to suppress Auger recombination. Compared with their red and green counterparts, the larger reactivity difference between the alloyed shell precursors makes it hard to regulate the composition and structure of the shell, and the smaller potential barrier between the core and the alloyed shell in blue QDs renders charge carriers tunneling into surface defects easier. Here, we employ a Lewis soft base ligand, 1-decanethiol, to balance the mismatched reactivity between Zn and Cd precursors for crafting a thick gradient alloyed shell with gradually increased potential barrier, which can not only restrict the charge carriers tunneling but also smooth the confinement potential. As a result, the resulting blue QDs show a long Auger lifetime of 1.3 ns, and a low threshold of 6.9 µJ cm⁻² excited by a femtosecond laser, which is the record value among all reported blue-emitting nanocrystals and comparable to those of state-of-the-art red and green QDs.

中文翻译：

通过有效抑制俄歇复合实现蓝色量子点中的低阈值放大自发发射

蓝色量子点 (QD) 中放大的自发发射仍然受到其高阈值的限制，因为在设计具有宽带隙的 QD 中的合金核壳界面以抑制俄歇复合的挑战。与红色和绿色对应物相比，合金壳前驱体之间较大的反应性差异使其难以调节壳的组成和结构，并且蓝色 QD 中核与合金壳之间的势垒较小，使得电荷载流子隧穿进入表面缺陷更容易。在这里，我们采用路易斯软碱配体 1-癸硫醇来平衡 Zn 和 Cd 前体之间的错配反应性，以制造具有逐渐增加的势垒的厚梯度合金壳，这不仅可以限制电荷载流子隧穿，还可以平滑限制电位。结果，由此产生的蓝色 QD 显示出 1.3 ns 的长俄歇寿命和 6.9 µJ cm 的低阈值^-2由飞秒激光激发，这是所有报道的蓝色发射纳米晶体中的记录值，可与最先进的红色和绿色 QD 相媲美。

更新日期：2021-03-14

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