title: Dielectric properties of a CsPbBr3quantum dot solution in the terahertz region.
abstract: In recent years, CsPbBr3quantum dots (QDs) have attracted much attention due to their bright prospects in solar cell studies. Dielectric properties are important for the fabrication of optoelectronic devices. Here, the dielectric properties of a CsPbBr3QD solution are investigated between 0.1 and 2.0 THz by terahertz time-domain spectroscopy. The measured frequency-dependent transmitted ratio is found to decrease from 0.96 to 0.80 in this range. By comparing different concentrations of the QD solution, the frequency-averaged absorption is linearly increased with the increase in QD concentration. After that, the frequency-dependent dielectric constant, including the complex refractive index, complex dielectric constant, and conductivity, is extracted by Fourier transform of the time-domain spectrum. An effective medium approach method is adopted to extract the complex dielectric constant of a CsPbBr3QD inclusion, and a slight peak around 0.4 THz is found in the imaginary part of the dielectric constant. The result of Drude-Lorentz fitting shows that the phonon plays a dominant role in the dielectric properties of a CsPbBr3QD solution. Moreover, the THz response of a CsPbBr3QD is found to be unchanged when the test is conducted under illumination. We attribute this phenomenon to the discrete energy level of excitons in CsPbBr3QDs due to quantum confinement, and design a comparative experiment to validate it. This study is significant for its deeper insight into the dielectric properties of CsPbBr3QDs, and thus is helpful through its applications in optoelectronics.
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Yang
authors.forename: Xiangai
authors.initials: X
authors.lastname: Cheng
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.forename: Chao
authors.initials: C
authors.lastname: Shen
authors.forename: Zhongjie
authors.initials: Z
authors.lastname: Xu
authors.forename: Xin
authors.initials: X
authors.lastname: Zheng
authors.forename: Tian
authors.initials: T
authors.lastname: Jiang