pH-Dependent Photophysical Properties of Metallic Phase MoSe2 Quantum …
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논문명 | pH-Dependent Photophysical Properties of Metallic Phase MoSe2 Quantum Dots |
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저자 | Boemjin Ko, Jaegyu Ahn and Sung Ho Song |
저널명 | materials |
게재년월 | 2022/7/15 |
Vol. pp |
Fluorescence properties of quantum dots (QDs) are critically affected by their redox states,
which is important for practical applications. In this study, we investigated the optical properties
of MoSe2
-metallic phase quantum-dots (MoSe2
-mQDs) depending on the pH variation, in which
the MoSe2
-mQDs were dispersed in water with two sizes (Φ~3 nm and 12 nm). The larger MoSe2
-
mQDs exhibited a large red-shift and broadening of photoluminescence (PL) peak with a constant
UV absorption spectra as varying the pH, while the smaller ones showed a small red-shift and
peak broadening, but discrete absorption bands in the acidic solution. The excitation wavelengthdependent photoluminescence shows that the PL properties of smaller MoSe2
-mQDs are more
sensitive to the pH change compared to those of larger ones. From the time-resolved PL spectroscopy,
the excitons dominantly decaying with an energy of ~3 eV in pH 2 clearly show the shift of PL peak to
the lower energy (~2.6 eV) as the pH increases to 7 and 11 in the smaller MoSe2
-mQDs. On the other
hand, in the larger MoSe2
-mQDs, the exciton decay is less sensitive to the redox states compared to
those of the smaller ones. This result shows that the pH variation is more critical to the change of
photophysical properties than the size effect in MoSe2
-mQDs