Lifetime blinking in nonblinking nanocrystal quantum dots.
Lifetime blinking in nonblinking nanocrystal quantum dots.
复制标题
DOI：
10.1038/ncomms1916
复制
发表时间：
2012-06-19
影响因子：
16.6
通讯作者：
中科院分区：
文献类型：
--
作者：
纳米晶体量子点是应用于纳米级光源的极具吸引力的材料。这些应用的一个障碍是单点发射强度的波动，即所谓的闪烁。胶体合成的最新进展产生了不闪烁的纳米晶体；然而，闪烁抑制的物理原理仍然不清楚。本研究发现，超厚壳CdSe/CdS纳米晶体尽管具有稳定的非闪烁发射强度，但其发射寿命会出现明显的波动（寿命闪烁）。我们证明，寿命变化是由于纳米晶体的中性和负电荷状态之间的切换。负电荷导致更快的辐射衰减，但由于抑制了负离子的非辐射俄歇复合，因此不会明显改变总体发射强度。俄歇过程涉及激发一个空穴（正电子途径）仍然有效，并负责与多余的电子充电，这是通过俄歇辅助电离的双激子伴随着空穴的喷射发生。纳米晶体量子点可以表现出光致发光闪烁，其发射光的强度由于随机充放电而波动。Galland等研究厚壳纳米晶体，发现其光致发光寿命也可以发生闪烁，但强度不变。
Nanocrystal quantum dots are attractive materials for applications as nanoscale light sources. One impediment to these applications is fluctuations of single-dot emission intensity, known as blinking. Recent progress in colloidal synthesis has produced nonblinking nanocrystals; however, the physics underlying blinking suppression remains unclear. Here we find that ultra-thick-shell CdSe/CdS nanocrystals can exhibit pronounced fluctuations in the emission lifetimes (lifetime blinking), despite stable nonblinking emission intensity. We demonstrate that lifetime variations are due to switching between the neutral and negatively charged state of the nanocrystal. Negative charging results in faster radiative decay but does not appreciably change the overall emission intensity because of suppressed nonradiative Auger recombination for negative trions. The Auger process involving excitation of a hole (positive trion pathway) remains efficient and is responsible for charging with excess electrons, which occurs via Auger-assisted ionization of biexcitons accompanied by ejection of holes. Nanocrystal quantum dots can exhibit photoluminescence blinking, where the intensity of the emitted light fluctuates due to random charging and discharging. Galland et al. study thick shell nanocrystals and find that the photoluminescence lifetime can also undergo blinking, without intensity changes.
登录
查看更多内容
影响因子：
10.8
作者：
Garcia-Santamaria, Florencio;Brovelli, Sergio;Klimov, Victor I.
通讯作者：
Klimov, Victor I.
影响因子：
3.3
作者：
Houtepen, AJ;Vanmaekelbergh, D
通讯作者：
Vanmaekelbergh, D
影响因子：
8.6
作者：
Frantsuzov, Pavel A.;Volkan-Kacso, Sandor;Janko, Boldizsar
通讯作者：
Janko, Boldizsar
影响因子：
3.7
作者：
Klimov, V. I.;McGuire, J. A.;Rupasov, V. I.
通讯作者：
Rupasov, V. I.
影响因子：
56.9
作者：
Klimov, VI;Mikhailovsky, AA;Bawendi, MG
通讯作者：
Bawendi, MG