title: Ultralow-Threshold Single-Mode Lasing from Phase-Pure CdSe/CdS Core/Shell Quantum Dots.
abstract: The development of colloidal quantum dot (QD) lasers is blocked by Auger recombination (AR). Here, phase-pure wurtzite CdSe/CdS core/shell QDs with controlled shell thickness are reported, which possess nearly defect-free core/shell interfaces. Benefiting from increased volume, electron-hole partial spatial separation, and nearly defect-free alloyed interface, this series of QDs exhibit a greater than 3 orders of magnitude decrease in AR rates with increasing shell thickness. Consequently, the amplified spontaneous emission threshold of the QDs with an 11 monolayer CdS shell is found to reach a minimum of 16 μJ cm-2. A record long lifetime (>1000 ps) and extraordinarily large bandwidth (>170 nm) of optical gain are observed by employing ultrafast transient absorption spectroscopy. We leverage the low-threshold gain of the QDs to fabricate microlasers that display single-mode operation and an ultralow threshold of ∼2 μJ cm-2. Our results represent a valuable step toward practical QD lasers.
authors.affiliation: Advanced Photonic Center, Southeast University , Nanjing 210096, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Liao
authors.affiliation: Advanced Photonic Center, Southeast University , Nanjing 210096, China.
authors.forename: Ruilin
authors.initials: R
authors.lastname: Xu
authors.affiliation: National Laboratory of Solid State Microstructures, School of Physics, Nanjing University , Nanjing 210093, China.
authors.forename: Yanqing
authors.initials: Y
authors.lastname: Xu
authors.affiliation: National Laboratory of Solid State Microstructures, School of Physics, Nanjing University , Nanjing 210093, China.
authors.forename: Chunfeng
authors.initials: C
authors.lastname: Zhang
authors.affiliation: National Laboratory of Solid State Microstructures, School of Physics, Nanjing University , Nanjing 210093, China.
authors.forename: Min
authors.initials: M
authors.lastname: Xiao
authors.affiliation: Advanced Photonic Center, Southeast University , Nanjing 210096, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Advanced Photonic Center, Southeast University , Nanjing 210096, China.
authors.forename: Changgui
authors.initials: C
authors.lastname: Lu
authors.affiliation: Advanced Photonic Center, Southeast University , Nanjing 210096, China.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Advanced Photonic Center, Southeast University , Nanjing 210096, China.
authors.forename: Jiayu
authors.identifier: http://orcid.org/0000-0001-7868-6346
authors.initials: J
authors.lastname: Zhang