15:15 〜 15:30
▼ [13p-A37-7] Photoluminescence Quantum Yield and Effective Exciton Radiative Lifetime in Monolayer Transition Metal Dichalcogenides
キーワード：photoluminescence quantum yield, radiative lifetime, transition metal dichalcogenides
The discovery of graphene and its fascinating properties [1] motivates new research fields in two-dimensional (2D) atomically thin-layered materials. The semiconductor transition metal dichalcogenides (TMDs) with chemical formula of MX2, (M = Mo, W; X = S, Se, Te) have attracted great research interest due to its intriguing properties [2,3]. It is very crucial to know the photoluminescence (PL) quantum yield and exciton radiative lifetime of this material in both viewpoint of research and opto-electronic device applications [4].
In this study, monolayer tungsten diselenides (1L-WSe2) from mechanically exfoliation technique was experimentally evaluated its PL quantum yield, FPL and effective radiative lifetime, trad at room temperature. Figure 1(a) show that PL spectrum of 1L-WSe2 at power density of 1 kW/cm2 is mainly dominates by exciton, while the inset figure shows the integrated PL with varying power density in the linear region. In addition, PL quantum yield of 0.2 % was estimated using relative quantum yield method using highly fluorescent standard dye [5] as reference. We also conducted time-resolved PL spectroscopy measurement to measure the PL decay time of 1L-WSe2 at room temperature. The exciton effective radiative lifetime of 280 ns was determined using the PL quantum yield and PL decay time, tPL of ~ 560 ps (Figure 1(b)). This experimental result with considerably long exciton effective radiative lifetime compared to 5 ns of theoretical predicted value at room temperature [6], is suggested due to existence of the dark states. Our finding will provide some information for future development of TMDs application.
In this study, monolayer tungsten diselenides (1L-WSe2) from mechanically exfoliation technique was experimentally evaluated its PL quantum yield, FPL and effective radiative lifetime, trad at room temperature. Figure 1(a) show that PL spectrum of 1L-WSe2 at power density of 1 kW/cm2 is mainly dominates by exciton, while the inset figure shows the integrated PL with varying power density in the linear region. In addition, PL quantum yield of 0.2 % was estimated using relative quantum yield method using highly fluorescent standard dye [5] as reference. We also conducted time-resolved PL spectroscopy measurement to measure the PL decay time of 1L-WSe2 at room temperature. The exciton effective radiative lifetime of 280 ns was determined using the PL quantum yield and PL decay time, tPL of ~ 560 ps (Figure 1(b)). This experimental result with considerably long exciton effective radiative lifetime compared to 5 ns of theoretical predicted value at room temperature [6], is suggested due to existence of the dark states. Our finding will provide some information for future development of TMDs application.