11:00 〜 11:15
▲ [12a-W521-9] Stability of monolayer WSe2 and MoS2 in an aqueous solution under light irradiation
キーワード：transition metal dichalcogenides
Atomically thin transition metal dichalcogenides (TMDCs) MX2, where M and X are a transition metal and a chalcogen, respectively, have become attractive candidate for future electronics and optoelectronics applications such as gas/bio sensors and photocatalyst because of their unique optical and electrical properties[1-4]. Due to their extremely large specific surface area, their physical or chemical performances and stabilities are easily affected by the surface electrochemical interactions between TMDCs and their environment[5]. Thus, it is important to clarify the impact of surface interactions on the stability of TMDCs for their real applications.
Here we report the stability of monolayer (1L) WSe2 and MoS2 under light irradiation in aqueous solutions with various pH. We probed degradation of the sample as a function of time using photoluminescence (PL) spectroscopy. PL properties in air and aqueous solutions were compared for 1L-WSe2 and 1L-MoS2.
Figure 1 shows the PL intensity change of 1L-WSe2 and 1L-MoS2 in distilled water (pH = 7) under visible light irradiation (580 nm, 800 W/cm2). The PL intensities of 1L-WSe2 show remarkable decrease whereas 1L-MoS2 were stable. These results suggest that only 1L-WSe2 was degraded. These differences are mainly attributed to the different surface reactions between 1L-TMDCs and O2/H2O redox couple; the difference is induced by the alignments of band levels of 1L-WSe2(MoS2) and O2/H2O redox potentials and photo-generated holes.
Here we report the stability of monolayer (1L) WSe2 and MoS2 under light irradiation in aqueous solutions with various pH. We probed degradation of the sample as a function of time using photoluminescence (PL) spectroscopy. PL properties in air and aqueous solutions were compared for 1L-WSe2 and 1L-MoS2.
Figure 1 shows the PL intensity change of 1L-WSe2 and 1L-MoS2 in distilled water (pH = 7) under visible light irradiation (580 nm, 800 W/cm2). The PL intensities of 1L-WSe2 show remarkable decrease whereas 1L-MoS2 were stable. These results suggest that only 1L-WSe2 was degraded. These differences are mainly attributed to the different surface reactions between 1L-TMDCs and O2/H2O redox couple; the difference is induced by the alignments of band levels of 1L-WSe2(MoS2) and O2/H2O redox potentials and photo-generated holes.