Exciton‐Like and Mid‐Gap Absorption Dynamics of PtS in Resonant and Transparent Regions

Abstract

Two essential ranges of energy within and out of bandgap determine the global optical property of a general semiconductor. Here, exciton-like inter-sub-band resonance absorption and optical bleaching of platinum sulfide (PtS) in the resonant region are found and investigated through the linear optical spectra and ultrafast transient absorption spectra. Besides, free-carrier absorption and defect-assisted Auger recombination in the transparent region are identified via the intensity-and temperature-dependent pump-probe experiments. Good experimental and theorical agreements are obtained using the mid-gap carrier-capture model considering the complex optical conductivity based on the rate equations. This work facilitates further understanding of the ultrafast photoinduced carrier behavior in PtS, which provides the possibility for future applications in photoelectric devices.

Interface State Assisted Ultrafast Carrier Dynamics in Core–Shell Structure ZIF-8@ZIF-67

“…Then the absorption of the excited sample to the probe laser is less than that of the unexcited sample, which is also known as photobleaching. 33 In subsequent process II, ΔA gradually increases from a negative valley value to a positive peak value. This maximum peak is called the PA peak and can be attributed to the relaxation and thermalization of hot carriers or excited-state absorption.…”

“…In this process, the ground-state electrons absorb the pump laser and then transition to the excited state, reducing the population of ground-state electrons and increasing the population of excited-state electrons. Then the absorption of the excited sample to the probe laser is less than that of the unexcited sample, which is also known as photobleaching . In subsequent process II, Δ A gradually increases from a negative valley value to a positive peak value.…”

“…In subsequent process II, Δ A gradually increases from a negative valley value to a positive peak value. This maximum peak is called the PA peak and can be attributed to the relaxation and thermalization of hot carriers or excited-state absorption. − That is, the ground-state particles transition to the excited state after being excited by the pump laser, due to the sample having rich excited-state energy levels; when the probe laser is incident, the excited-state particles absorb the probe light and then transition to a higher-excited-state energy level. Subsequently, in process III, Δ A drops sharply from its maximum and remains essentially unchanged thereafter, a process known as Auger recombination .…”

Enhanced nonlinear optical response and ultrafast carrier dynamics in amorphous Fe-doped ZIF-67

“…This maximum peak is called the photoinduced absorption (PA) peak and can be attributed to the hot carrier's relaxation and thermalization process or excited-state absorption. 38–40 Subsequently, Δ A in region III dropped rapidly from its maximum and remained essentially constant thereafter. This long recovery process in region III is mainly attributed to the Auger recombination process.…”

“…DA rapidly drops to a negative valley value in process I, because the electrons of the ground state absorption pump light transition to the excited state, resulting in a decrease in the population of the ground state electrons, an increase in the population of the excited state electrons, and the absorption of the excited sample to the probe light is less than that of the unexcited sample to the probe light, that is, photoinduced bleaching (PB). 38 In the subsequent II process in the range of about 0.5 ps, DA gradually increases to a positive value and a maximum peak appears. This maximum peak is called the photoinduced absorption (PA) peak and can be attributed to the hot carrier's relaxation and thermalization process or excited-state absorption.…”