Tanghe Ivo, Samoli Margarita, Wagner Isabella, Cayan Servet Ataberk, Khan Ali Hossain, Chen Kai, Hodgkiss Justin, Moreels Iwan, Thourhout Dries Van, Hens Zeger, Geiregat Pieter
Photonics Research Group, Ghent University, Gent, Belgium.
NoLIMITS Center For Non-Linear Microscopy and Spectroscopy, Ghent University, Gent, Belgium.
Nat Nanotechnol. 2023 Dec;18(12):1423-1429. doi: 10.1038/s41565-023-01521-0. Epub 2023 Oct 5.
Strongly confined colloidal quantum dots have been investigated for low-cost light emission and lasing for nearly two decades. However, known materials struggle to combine technologically relevant metrics of low-threshold and long inverted-state lifetime with a material gain coefficient fit to match cavity losses, particularly under electrical excitation. Here we show that bulk nanocrystals of CdS combine an exceptionally large material gain of 50,000 cm with best-in-class gain thresholds below a single exciton per nanocrystal and 3 ns gain lifetimes not limited by non-radiative Auger processes. We quantitatively account for these findings by invoking a strong bandgap renormalization effect, unobserved in nanocrystals to date, to the best of our knowledge. Next, we demonstrate broadband amplified spontaneous emission and lasing under quasi-continuous-wave conditions. Our results highlight the prospects of bulk nanocrystals for lasing from solution-processable materials.
近二十年来，人们一直在研究强受限胶体量子点用于低成本发光和激光发射。然而，已知材料难以将低阈值和长反转态寿命等技术相关指标与适合匹配腔损耗的材料增益系数相结合，特别是在电激发下。在这里，我们表明硫化镉体相纳米晶体结合了高达50000 cm的异常大的材料增益，具有同类最佳的增益阈值，低于每个纳米晶体一个单激子，且3 ns的增益寿命不受非辐射俄歇过程限制。据我们所知，通过引入一种迄今为止在纳米晶体中未观察到的强带隙重整化效应，我们对这些发现进行了定量解释。接下来，我们展示了在准连续波条件下的宽带放大自发发射和激光发射。我们的结果突出了体相纳米晶体在可溶液加工材料激光发射方面的前景。
