The density of electron states, p(E), in disordered systems in the band-tail region near band edges is investigated. %'e show that the p(E) of the Halperin and Lax type derived by Sa-yakanit predicts, in three dimensions, an exponential (Urbach) band tail for the correlation lengths found in amorphous Si and within the energy range observed in optical absorption near band edges. The simple expo...

The role of structural and dynamical disorder in semiconductors is a topic fundamental relevance because its contribution to the spectral line shape photoluminescence, it plays major ruling carrier transport properties at band edge. In this regard, class semiconductors, i.e., halide perovskites, deeply investigated last decade, shows peculiar degree disorder, which has only been recently under ...

Abstract We propose new optical dispersion models to describe the imaginary part of electrical permittivity dielectric and semiconductor materials in fundamental absorption region. work out our procedure based on well-known structure semi-empirical Tauc–Lorentz model band-fluctuations approach derive a five-parameter formula that describes Urbach, Tauc high-absorption regions direct indirect se...

The photovoltage Voc of high-performance solar cells such as GaAs and metal halide perovskites is affected by the exponential Urbach tail in absorption spectrum, with an energy parameter EU. It has been observed that increasing decreases maximum can be achieved. On basis detailed balance reciprocity emission, we present a calculation shows voltage loss due to obeys universal relation ΔVocrad = ...

Lead halide perovskites possess high photoluminescence (PL) efficiency and strong electron-phonon interactions, therefore optical cooling using up-conversion PL has been expected. We investigate anti-Stokes from green-luminescent ${\mathrm{Cs}}_{4}{\mathrm{PbBr}}_{6}$, whose origin is attributable to ${\mathrm{CsPbBr}}_{3}$ nanostructures embedded in a ${\mathrm{Cs}}_{4}{\mathrm{PbBr}}_{6}$ cry...

Thin films of GeTe2 were deposited on glass substrates using radio-frequency magnetron sputtering with various hydrogen flow rates in the growth chamber. Transmission data of deposited films were taken and used to determine optical constants refractive index n , extinction coefficient , and absorption coefficient and the energies corresponding to absorption coefficients of 104 and 103 cm−1 E04,...