posted on 2021-02-25, 18:05authored bySavas Delikanli, Onur Erdem, Furkan Isik, Hamed Dehghanpour Baruj, Farzan Shabani, Huseyin Bilge Yagci, Emek Goksu Durmusoglu, Hilmi Volkan Demir
We demonstrate amplified spontaneous
emission (ASE) in solution
with ultralow thresholds of 30 μJ/cm2 in red and
of 44 μJ/cm2 in green from engineered colloidal quantum
well (CQW) heterostructures. For this purpose, CdSe/CdS core/crown
CQWs, designed to hit the green region, and CdSe/CdS@CdxZn1–xS core/crown@gradient-alloyed
shell CQWs, further tuned to reach the red region by shell alloying,
were employed to achieve high-performance ASE in the visible range.
The net modal gain of these CQWs reaches 530 cm–1 for the green and 201 cm–1 for the red, 2–3
orders of magnitude larger than those of colloidal quantum dots (QDs)
in solution. To explain the root cause for ultrahigh gain coefficient
in solution, we show for the first time that the gain cross sections
of these CQWs is ≥3.3 × 10–14 cm2 in the green and ≥1.3 × 10–14 cm2 in the red, which are two orders of magnitude larger
compared to those of CQDs.