Delikanli Savas, Isik Furkan, Durmusoglu Emek G, Erdem Onur, Shabani Farzan, Canimkurbey Betul, Kumar Satish, Dehghanpour Baruj Hamed, Demir Hilmi Volkan
Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey.
Nanoscale. 2022 Oct 21;14(40):14895-14901. doi: 10.1039/d2nr03659b.
Although achieving optical gain using aqueous solutions of colloidal nanocrystals as a gain medium is exceptionally beneficial for bio-optoelectronic applications, the realization of optical gain in an aqueous medium using solution-processed nanocrystals has been extremely challenging because of the need for surface modification to make nanocrystals water dispersible while still maintaining their gain. Here, we present the achievement of optical gain in an aqueous medium using an advanced architecture of CdSe/CdS@CdZnS core/crown@gradient-alloyed shell colloidal quantum wells (CQWs) with an ultralow threshold of ∼3.4 μJ cm and an ultralong gain lifetime of ∼2.6 ns. This demonstration of optical gain in an aqueous medium is a result of the carefully heterostructured CQWs having large absorption cross-section and gain cross-section in addition to inherently slow Auger recombination in these CQWs. Furthermore, we show low-threshold in-water amplified spontaneous emission (ASE) from these aqueous CQWs with a threshold of 120 μJ cm. In addition, we demonstrate a whispering gallery mode laser with a low threshold of ∼30 μJ cm obtained by incorporating films of CQWs by exploiting layer-by-layer approach on a fiber. The observation of low-threshold optical gain with ultralong gain lifetime presents a significant step toward the realization of advanced optofluidic colloidal lasers and their continuous-wave pumping.
尽管使用胶体纳米晶体水溶液作为增益介质来实现光学增益对于生物光电子应用极为有益，但由于需要进行表面改性以使纳米晶体在水中可分散同时仍保持其增益，因此利用溶液处理的纳米晶体在水介质中实现光学增益极具挑战性。在此，我们展示了使用具有约3.4 μJ/cm超低阈值和约2.6 ns超长增益寿命的CdSe/CdS@CdZnS核/冠@梯度合金壳胶体量子阱（CQW）的先进结构在水介质中实现光学增益。在水介质中实现光学增益这一成果是精心设计的异质结构CQW的结果，这些CQW除了具有固有的缓慢俄歇复合外，还具有大的吸收截面和增益截面。此外，我们展示了来自这些水性CQW的低阈值水中放大自发发射（ASE），其阈值为120 μJ/cm。此外，我们通过在光纤上利用逐层方法并入CQW薄膜，展示了一种阈值约为30 μJ/cm的低阈值回音壁模式激光器。超低阈值光学增益与超长增益寿命的观测是朝着实现先进的光流体胶体激光器及其连续波泵浦迈出的重要一步。
