Phonon-assisted upconversion in twisted two-dimensional semiconductors  

作　　者：Yuchen Dai Pengfei Qi Guangyi Tao Guangjie Yao Beibei Shi Zhixin Liul Zhengchang Liu Xiao He Pu Peng Zhibo Dang Liheng Zheng Tianhao Zhang Yongji Gong Yan Guan Kaihui Liu Zheyu Fang 

机构地区：[1]School of Physics,State Key Laboratory for Mesoscopic Physics,Academy for Advanced Interdisciplinary Studies,Collaborative Innovation Center of Quantum Matter,Nano-optoelectronics Frontier Center of Ministry of Education,Peking University,100871 Beijing,China [2]Institute of Modern Optics,Nankai University,Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology,300350 Tianjin,China [3]Photonics Research Center,School of Physics,MOE Key Lab of Weak-Light Nonlinear Photonics,and Tianjin Key Lab of Photonics Materials and Technology for Information Science,Nankai University,300071 Tianjin,China [4]School of Materials Science and Engineering,Beihang University,100191 Beijing,China [5]Center for Physicochemical Analysis and Measurements in ICCAS,Analytical Instrumentation Center,Peking University,100871 Beijing,China

出　　处：《Light(Science & Applications)》2023年第1期89-98,共10页光（科学与应用)（英文版）

基　　金：supports from the National Key Research and Development Program of China(2020YFA0211300);National Science Foundation of China(grant Nos.62225501,12027807);Bejing Natural Science Foundation(grant Nos.Z180011);High-performance Computing Platform of Peking University.

摘　　要：Phonon-assisted photon upconversion(UPC)is an anti-Stokes process in which incident photons achieve higher energy emission by absorbing phonons.This letter studies phonon-assisted UPC in twisted 2D semiconductors,in which an inverted contrast between UPC and conventional photoluminescence(PL)of WSe2 twisted bilayer is emergent.A 4-fold UPC enhancement is achieved in 5.5°twisted bilayer while PL weakens by half.Reduced interlayer exciton conversion efficiency driven by lattice relaxation,along with enhanced pump efficiency resulting from spectral redshift,lead to the rotation-angle-dependent UPC enhancement.The counterintuitive phenomenon provides a novel insight into a unique way that twisted angle affects UPC and light-matter interactions in 2D semiconductors.Furthermore,the UPC enhancement platform with various superimposable means offers an effective method for lighting bilayers and expanding the application prospect of 2D stacked van der Waals devices.

关 键 词：TWISTED SEMICONDUCTORS RELAXATION 

分 类 号：O15[理学—数学]