Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun, 130024, China.
CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China.
Small. 2017 May;13(17). doi: 10.1002/smll.201700157. Epub 2017 Mar 1.
It is very important to obtain a deeper understand of the carrier dynamics for indirect-bandgap multilayer MoS and to make further improvements to the luminescence efficiency. Herein, an anomalous luminescence behavior of multilayer MoS is reported, and its exciton emission is significantly enhanced at high temperatures. Temperature-dependent Raman studies and electronic structure calculations reveal that this experimental observation cannot be fully explained by a common mechanism of thermal-expansion-induced interlayer decoupling. Instead, a new model involving the intervalley transfer of thermally activated carriers from Λ/Γ point to K point is proposed to understand the high-temperature luminescence enhancement of multilayer MoS . Steady-state and transient-state fluorescence measurements show that both the lifetime and intensity of the exciton emission increase relatively to increasing temperature. These two experimental evidences, as well as a calculation of carrier population, provide strong support for the proposed model.
深入了解间接带隙多层 MoS 的载流子动力学对于进一步提高发光效率非常重要。本文报道了多层 MoS 的异常发光行为，其激子发射在高温下显著增强。温度依赖的拉曼研究和电子结构计算表明，这种实验观察不能用常见的热膨胀诱导层间去耦机制来完全解释。相反，提出了一个涉及热激活载流子从 Λ/Γ点到 K 点的谷间转移的新模型，以理解多层 MoS 的高温发光增强。稳态和瞬态荧光测量表明，随着温度的升高，激子发射的寿命和强度都相对增加。这两个实验证据，以及载流子数的计算，为所提出的模型提供了有力支持。
