Optical properties of PbTe and PbSe

Temperature dependent band gap in PbX (X = S, Se, Te)

“…7 P-type PbTe has a complex valence band structure that involves a light band at the L point (direct gap) and a region of electronic states centered along the R line. This region along the R line has been described and modeled as a separate, heavy band, even though recent work suggests it may be associated with the band at L. [8][9][10] However, twoband analysis, e.g., when both bands are considered separately, is consistent with most experimental observations and is useful for rational thermoelectric material design. 3,7,11,12 Based on historical evidence [13][14][15] and calculations, 9,10,16,17 the band extremum at R is believed to lie about 0.1-0.15 eV below that of the band at L at room temperature (see Figure 1(d)).…”

“…Optical data on single crystalline bulk samples and films of lead chalcogenides have been obtained using a variety of measurement techniques, [24][25][26][27][28][29][30] but the analysis of these results, including the reported observation of band convergence, have recently been questioned. 8,10 Here, we perform measurements using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) on polycrystalline samples and use ab initio molecular dynamics (AIMD) to study the temperature dependent gap and to examine the band structure at high temperatures. DRIFTS has been shown to be a reliable technique capable of quantifying small shifts in the electronic band structure, especially the band gap with high resolution (60.004 eV).…”

“…Still, the exact band energies and their temperature dependence continue to be disputed. [7][8][9][10] Knowledge of the specific band offset and its temperature dependence in these materials is crucial since band convergence is thought to be responsible for the improved thermoelectric properties. Hence, this work is motivated by the hope that a more accurate understanding of the electronic band structure can provide a clearer route forward to band structure engineering in the lead chalcogenides for further improvement of zT.…”

Electronic, optical, and thermoelectric properties of Fe2+xV1−xAl

“…For example, a recent theoretical study showed that doping of Re and Ru atoms for Mn in AlMnSi C54-phase could drastically increase its ZT from 0.12 to 0.38 at 540 K. 26 In this paper, we investigate the electronic, magnetic, optical, and thermoelectric properties of Fe 2 VAl with Fe antisite defects (Fe 2+x V 1x Al) as obtained from the modern band structure computations with the recently developed Tran and Blaha modified Becke-Johnson potential functional (denoted as TB-mBJ). 27,28 The TB-mBJ functional yields band gaps in good agreement with experiment [29][30][31][32] in contrast to the local density approximation (LDA) or the generalized gradient approximation (GGA) functionals. Hence, enables direct, quantitative comparisons of optoelectronic properties with experiment, without any adjustments, such as scaling the magnitude of the absorption or applying scissors operators to fix the gap.…”

Advancing colloidal quantum dot photovoltaic technology

“…PbS and PbSe possess small bulk band gaps, 0.41 and 0.27 eV, respectively [52,62], making them ideal candidates for tuning the absorption spectra throughout the near-IR portion of the sun's spectrum. CdS and CdSe, with larger bulk band gaps of 2.42 and 1.74 eV, respectively, have found use in sensitized solar cell (SSC) architectures, and are of more interest for visible-wavelength applications [63,64].…”