期刊
ACS NANO
卷 13, 期 9, 页码 10662-10670出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.9b04967
关键词
colloidal quantum wells; nanoplatelets; hot-injection growth; optical gain; single-mode lasing; VCSEL
类别
资金
- Singapore National Research Foundation [NRF-NRFI2016-08]
- Science and Engineering Research Council, Agency for Science, Technology and Research (A*STAR) of Singapore
- TUBITAK [115E679, 117E713]
- TUBA
- TUBA-GEBIP
- Abdullah Gul University Scientific Research Project [FDK-2017-96]
- TUBITAK BIDEB 2211 program
As an attractive materials system for high- Record-low optical gain threshold in giant-shell COWs performance optoelectronics, colloidal nanoplatelets (NPLs) benefit from atomic-level precision in thickness, minimizing emission inhomogeneous broadening. Much progress has been made to enhance their photoluminescence quantum yield (PLQY) and photostability. However, to date, layer-by-layer growth of shells at room temperature has resulted in defects that limit PLQY and thus curtail the 0.2 performance of NPLs as an optical gain medium. Here, we introduce a hot-injection method growing giant alloyed shells using an approach that reduces core/shell lattice mismatch and suppresses Auger recombination. Near-unity PLQY is achieved with a narrow full-width-at-half-maximum (20 nm), accompanied by emission tunability (from 610 to 650 nm). The biexciton lifetime exceeds 1 ns, an order of magnitude longer than in conventional colloidal quantum dots (CQDs). Reduced Auger recombination enables record-low amplified spontaneous emission threshold of 2.4 mu J cm(-2) under one-photon pumping. This is lower by a factor of 2.5 than the best previously reported value in nanocrystals (6 /kJ cm(-2) for CdSe/CdS NPLs). Here, we also report single-mode lasing operation with a 0.55 mu J cm(-2) threshold under two-photoexcitation, which is also the best among nanocrystals (compared to 0.76 mu J cm(-2) from CdSe/CdS CQDs in the Fabry-Perot cavity). These findings indicate that hot-injection growth of thick alloyed shells makes ultrahigh performance NPLs.
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