Linear Relationship between the Dielectric Constant and Band Gap in Low-Dimensional Mixed-Halide Perovskites

2021 ◽  
Author(s):  
Yujing Dong ◽  
Rui Zhu ◽  
Yu Jia
Keyword(s):  
Dielectric Constant ◽  
Linear Relationship ◽  
Band Gap ◽  
Halide Perovskites ◽  
Low Dimensional

SIZE-DEPENDENT BAND-GAP AND DIELECTRIC CONSTANT OF SI NANOCRYSTALS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2297-2301 ◽  
Author(s):  
M. LI ◽  
J. C. LI ◽  
Q. JIANG
Keyword(s):  
Thin Films ◽  
Computer Simulation ◽  
Dielectric Constant ◽  
Band Gap ◽  
Adjustable Parameter ◽  
Size Dependent ◽  
Si Nanocrystals ◽  
Simulation Results ◽  
Low Dimensional ◽  
Low Dimensional Materials

Based on the consideration on size-dependent temperature Tm(D) where D denotes the diameter of nanoparticles and nanowires or the thickness of thin films, the size-dependent band-gap ΔEg(D) and dielectric constant ε(D) of low dimensional materials are modeled without any adjustable parameter. The model predicts an increase of the band-gap and a decrease of dielectric constant with drop of Si nanocrystals' size. The predicted results correspond to experimental and computer simulation results of Si nanocrystals.

Advances of Nonlinear Photonics in Low‐Dimensional Halide Perovskites

Small ◽  
2021 ◽  
pp. 2100809
Author(s):  
Gang Wang ◽  
Shiliang Mei ◽  
Jinfeng Liao ◽  
Wei Wang ◽  
Yuxin Tang ◽  
...  
Keyword(s):  
Halide Perovskites ◽  
Low Dimensional ◽  
Nonlinear Photonics

scholarly journals Characteristics of Poly(vinyl Alcohol) (PVA) Based Composites Integrated with Green Synthesized Al3+-Metal Complex: Structural, Optical, and Localized Density of State Analysis

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1316
Author(s):  
Shujahadeen B. Aziz ◽  
Muaffaq M. Nofal ◽  
Hewa O. Ghareeb ◽  
Elham M. A. Dannoun ◽  
Sarkawt A. Hussen ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Metal Complex ◽  
Band Gap ◽  
Optical Band Gap ◽  
Complex Dielectric Constant ◽  
Poly Vinyl Alcohol ◽  
Optical Parameters ◽  
Dispersion Energy ◽  
Casting Technique

The influence of dispersing Al-metal complex on the optical properties of PVA was investigated using UV–visible spectroscopy. Polymer composite films with various Al3+-complex amounts in the PVA matrix were arranged by solution casting technique by means of distilled water as a widespread solvent. The formation of Al3+-metal complex was verified through Ultraviolet–visible (UV-Vis) and Fourier-transform infrared spectroscopy (FTIR) examinations. The addition of Al-complex into the polymer matrix led to the recovery of the optical parameters such as dielectric constant (εr and εi) and refractive index (n). The variations of real and imaginary parts of complex dielectric constant as a function of photon wavelength were studied to calculate localized charge density values (N/m*), high-frequency dielectric constant, relaxation time, optical mobility, optical resistivity, and plasma angular frequency (ωp) of electrons. In proportion with Al3+-complex content, the N/m* values were amplified from 3.68 × 1055 kg−1 m−3 to 109 × 1055 kg−1 m−3. The study of optical parameters may find applications within optical instrument manufacturing. The optical band gap was determined from Tauc’s equation, and the type of electronic transition was specified. A remarkable drop in the optical band gap was observed. The dispersion of static refractive index (no) of the prepared composites was analyzed using the theoretical Wemple–DiDomenico single oscillator model. The average oscillator energy (Eo) and oscillator dispersion energy (Ed) parameters were estimated.

scholarly journals Effect of thickness on the optical properties of Gaas thin films

2013 ◽  
Vol 37 (1) ◽  
pp. 83-91 ◽  
Author(s):  
Chitra Das ◽  
Jahanara Begum ◽  
Tahmina Begum ◽  
Shamima Choudhury
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Band Gap ◽  
Optical Band Gap ◽  
Visible Region ◽  
Solar Spectrum ◽  
Band Gap Energy ◽  
Optical Parameters ◽  
Gap Energy

Effect of thickness on the optical and electrical properties of gallium arsenide (GaAs) thin films were studied. The films of different thicknesses were prepared by vacuum evaporation method (~10-4 Pa) on glass substrates at a substrate temperature of 323 K. The film thickness was measured in situ by a frequency shift of quartz crystal. The thicknesses were 250, 300 and 500 nm. Absorption spectrum of this thin film had been recorded using UV-VIS-NIR spectrophotometer in the photon wavelength range of 300 - 2500 nm. The values of some important optical parameters of the studied films (absorption coefficient, optical band gap energy and refractive index; extinction co-efficient and real and imaginary parts of dielectric constant) were determined using these spectra. Transmittance peak was observed in the visible region of the solar spectrum. Here transmittance showed better result when thicknesses were being increased. The optical band gap energy was decreased by the increase of thickness. The refractive index increased by increasing thickness while extinction co-efficient and real and imaginary part of dielectric constant decreased. DOI: http://dx.doi.org/10.3329/jbas.v37i1.15684 Journal of Bangladesh Academy of Sciences, Vol. 37, No. 1, 83-91, 2013

scholarly journals Low dimensional metal halide perovskites and hybrids

2019 ◽  
Vol 137 ◽  
pp. 38-65 ◽  
Author(s):  
Chenkun Zhou ◽  
Haoran Lin ◽  
Qingquan He ◽  
Liangjin Xu ◽  
Michael Worku ◽  
...  
Keyword(s):  
Metal Halide ◽  
Halide Perovskites ◽  
Low Dimensional
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