Zheng Ting, Lin Yu-Chuan, Yu Yiling, Valencia-Acuna Pavel, Puretzky Alexander A, Torsi Riccardo, Liu Chenze, Ivanov Ilia N, Duscher Gerd, Geohegan David B, Ni Zhenhua, Xiao Kai, Zhao Hui
School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China.
Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045, United States.
Nano Lett. 2021 Jan 27;21(2):931-937. doi: 10.1021/acs.nanolett.0c03412. Epub 2021 Jan 6.
We report here details of steady-state and time-resolved spectroscopy of excitonic dynamics for Janus transition metal dichalcogenide monolayers, including MoSSe and WSSe, which were synthesized by low-energy implantation of Se into transition metal disulfides. Absorbance and photoluminescence spectroscopic measurements determined the room-temperature exciton resonances for MoSSe and WSSe monolayers. Transient absorption measurements revealed that the excitons in Janus structures form faster than those in pristine transition metal dichalcogenides by about 30% due to their enhanced electron-phonon interaction by the built-in dipole moment. By combining steady-state photoluminescence quantum yield and time-resolved transient absorption measurements, we find that the exciton radiative recombination lifetime in Janus structures is significantly longer than in their pristine samples, supporting the predicted spatial separation of the electron and hole wave functions due to the built-in dipole moment. These results provide fundamental insight in the optical properties of Janus transition metal dichalcogenides.
我们在此报告了对Janus过渡金属二硫属化物单层（包括通过将硒低能注入过渡金属二硫化物中合成的MoSSe和WSSe）激子动力学的稳态和时间分辨光谱的详细信息。吸光度和光致发光光谱测量确定了MoSSe和WSSe单层在室温下的激子共振。瞬态吸收测量表明，由于Janus结构中内置偶极矩增强了电子 - 声子相互作用，其激子形成速度比原始过渡金属二硫属化物中的激子快约30%。通过结合稳态光致发光量子产率和时间分辨瞬态吸收测量，我们发现Janus结构中的激子辐射复合寿命明显长于其原始样品，这支持了由于内置偶极矩导致电子和空穴波函数发生空间分离的预测。这些结果为Janus过渡金属二硫属化物的光学性质提供了基本见解。
