Temperature-Dependent Phonon Scattering and Photoluminescence in Vertical MoS2/WSe2 Heterostructures

Abstract

Transition metal dichalcogenide (TMD) monolayers and their heterostructures have attracted considerable attention due to their distinct properties. In this work, we performed a systematic investigation of MoS2/WSe2 heterostructures, focusing on their temperature-dependent Raman and photoluminescence (PL) characteristics in the range of 79 to 473 K. Our Raman analysis revealed that both the longitudinal and transverse modes of the heterostructure exhibit linear shifts towards low frequencies with increasing temperatures. The peak position and intensity of PL spectra also showed pronounced temperature dependency. The activation energy of thermal-quenching-induced PL emissions was estimated as 61.5 meV and 82.6 meV for WSe2 and MoS2, respectively. Additionally, we observed that the spectral full width at half maximum (FWHM) of Raman and PL peaks increases as the temperature increases, and these broadenings can be attributed to the phonon interaction and the expansion of the heterostructure’s thermal coefficients. This work provides valuable insights into the interlayer coupling of van der Waals heterostructures, which is essential for understanding their potential applications in extreme temperatures.

Exciton Dynamics of TiOPc/WSe2 Heterostructure

“…As observed in Figure a, in the case of the bare WSe 2 , its PL undergoes a red-shift and thermal quenching as the temperature increases from −120 to 120 °C, which can be attributed to enhanced electron–phonon coupling and nonradiative recombination. The observation aligns with the temperature characteristics commonly observed in 2D semiconductors. , In the case of the TiOPc/WSe 2 , the emission peak position at 1.53 eV remains almost unchanged with the temperature increases from −120 to 120 °C. However, its intensity is gradually reduced, suggesting significant thermal quenching occurs.…”

“…The observation aligns with the temperature characteristics commonly observed in 2D semiconductors. 51,52 In the case of the TiOPc/WSe 2 , the emission peak position at 1.53 eV remains almost unchanged with the temperature increases from −120 to 120 °C. However, its intensity is gradually reduced, suggesting significant thermal quenching occurs.…”