Temperature dependence of photoluminescence lifetime of atomically-thin WSe₂ layer

Abstract

At cryogenic temperatures, the photoluminescence spectrum of monolayer WSe2 features a number of lines related to the recombination of so-called localized excitons. The intensity of these lines strongly decreases with increasing temperature. In order to understand the mechanism behind this phenomenon we carried out a time-resolved experiment, which revealed a similar trend in the photoluminescence decay time. Our results identify the opening of additional nonradiative relaxation channels as a primary cause of the observed temperature quenching of the localized excitons' photoluminescence.

Experimental and Theoretical Investigations of Direct and Indirect Band Gaps of WSe2

“…This may lead to more electronic states slightly higher than the CBM and create photon emissions with a larger energy. This observation is different from prior PL reports of 1L-WSe 2 , where a monotonic increase in PL intensity was measured as the temperature was decreased [ 32 , 33 ]. We attribute the difference to a better sample quality in our case, which quantitatively matches with the DFT calculation for the temperature boundary of direct-to-indirect bandgap transition.…”

“…Temperature and power-dependent PL tests of monolayer WSe 2 have been conducted to investigate the variations in PL peaks, and the linear relationship between PL peak intensity and temperature or laser power has been observed and discussed, elucidating underlying principles such as competitions between localized and delocalized exciton emissions [ 32 ] or the opening of additional non-radiative relaxation channels [ 33 ]. In this study, we endeavor to examine the relationship between temperature and PL peak position and elucidate its underlying mechanisms through Density Functional Theory (DFT) calculations.…”

Thickness-dependent excitonic properties of WSe2/FePS3 van der Waals heterostructures

“…The PL yield and spectral shape of monolayer WSe 2 are both consistent with previously reported results. 33 Under the same PL measurement conditions, FePS 3 shows no detectable signal and the heterostructure shows only one PL peak belonging to WSe 2 . It is noted that there does occur a PL quenching in the heterostructure in comparison with the isolated WSe 2 , and the quenching effect becomes more obvious as the FePS 3 thickness increases.…”

Ultrahigh Polarization-Sensitive Raman Scattering and Photon Emission in a Plasmonic Au/Biphenyl-4-thiol/Ag Nanowire Nanocavity

“…Therefore, the possibility of the Y 1 peak originating from defects seems to be low. In addition, the appearance of Y 1 and Y 2 peaks is also not likely to be local excitons 42,43 because the local exciton of WSe 2 is usually observed below 60 K with a similar intensity to the exciton at 4 K. 42 The most possible cause of Y 1 and Y 2 peaks is a strong plasmon−exciton coupling. Considering that surface plasmon polaritons (SPPs) propagating along the Ag NW can excite emitters in their propagation path, the strong near-field SPPs can also re-excite excitons around them.…”

“…Therefore, the possibility of the Y 1 peak originating from defects seems to be low. In addition, the appearance of Y 1 and Y 2 peaks is also not likely to be local excitons , because the local exciton of WSe 2 is usually observed below 60 K with a similar intensity to the exciton at 4 K . The most possible cause of Y 1 and Y 2 peaks is a strong plasmon–exciton coupling.…”