The optoelectronic properties of atomically thin transition metal dichalcogenides(TMDs)are largely influenced by defect populations(DPs).In this work,we fabricate WSmonolayers with different DPs by varying the fabrica...The optoelectronic properties of atomically thin transition metal dichalcogenides(TMDs)are largely influenced by defect populations(DPs).In this work,we fabricate WSmonolayers with different DPs by varying the fabrication methods and further reveal their distinct exciton-exciton interactions.Steady-state photoluminescence(PL)experiments show that the monolayer with the lowest DP shows optimal PL intensity at low excitation power;however,it is overtaken and significantly surpassed by monolayers with higher DPs at high excitation powers.Excitation-power-dependent experiments demonstrate that these monolayers exhibit distinct PL saturation behaviors with the threshold power differing by four orders of magnitude.Combined with in situ PL imaging and time-resolved PL experiments,we attribute such PL evolution discrepancies to the different DPs within these monolayers,which largely influence the exciton diffusion behavior and subsequently bring about distinct nonradiative exciton-exciton annihilations(EEAs).Valley polarization experiments are further employed to re-examine the DPs of these monolayers.This work reveals the distinct PL behaviors and underlying exciton dynamics in TMD monolayers with different DPs,which can largely facilitate the engineering of relevant high-performance devices for practical applications.展开更多
基金financially supported by the National Natural Science Foundation of China(52002125,U19A2090,62090035,51972105,61905071,and 52172140)China Postdoctoral Science Foundation(2020M672479 and 2020M680112)+4 种基金the Natural Science Foundation of Hunan Province(2021JJ40102 and 2021JJ30132)the Key Program of Science and Technology Department of Hunan Province(2019XK2001 and2020XK2001)the Science and Technology Innovation Program of Hunan Province(2020RC2028)the International Science and Technology Innovation Cooperation Base of Hunan Province(2018WK404)the Open Project Program of Wuhan National Laboratory for Optoelectronics(2020WNLOKF002)。
文摘The optoelectronic properties of atomically thin transition metal dichalcogenides(TMDs)are largely influenced by defect populations(DPs).In this work,we fabricate WSmonolayers with different DPs by varying the fabrication methods and further reveal their distinct exciton-exciton interactions.Steady-state photoluminescence(PL)experiments show that the monolayer with the lowest DP shows optimal PL intensity at low excitation power;however,it is overtaken and significantly surpassed by monolayers with higher DPs at high excitation powers.Excitation-power-dependent experiments demonstrate that these monolayers exhibit distinct PL saturation behaviors with the threshold power differing by four orders of magnitude.Combined with in situ PL imaging and time-resolved PL experiments,we attribute such PL evolution discrepancies to the different DPs within these monolayers,which largely influence the exciton diffusion behavior and subsequently bring about distinct nonradiative exciton-exciton annihilations(EEAs).Valley polarization experiments are further employed to re-examine the DPs of these monolayers.This work reveals the distinct PL behaviors and underlying exciton dynamics in TMD monolayers with different DPs,which can largely facilitate the engineering of relevant high-performance devices for practical applications.
