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Firsta??principles Investigation of the Structural, Elastic, Electronic, and Optical Properties of ?±a?? and ?2a??SrZrS3: Implications for Photovoltaic Applications
摘要： Transition metal perovskite chalcogenides are attractive solar absorber materials for renewable energy applications. Herein, we present the first–principles screened hybrid density functional theory analyses of the structural, elastic, electronic and optical properties of the two structure modifications of strontium zirconium sulfide (needle–like α–SrZrS3 and distorted β–SrZrS3 phases). Through the analysis of the predicted electronic structures, we show that both α– and β–SrZrS3 materials are direct band gaps absorbers, with calculated band gaps of 1.38, and 1.95 eV, respectively, in close agreement with estimates from diffuse–reflectance measurements. A strong light absorption in the visible region is predicted for the α– and β–SrZrS3, as reflected in their high optical absorbance (in the order of 105 cm?1), with the β–SrZrS3 phase showing stronger absorption than the α–SrZrS3 phase. We also report the first theoretical prediction of effective masses of photo‐generated charge carriers in α– and β–SrZrS3 materials. Predicted small effective masses of holes and electrons at the valence, and conduction bands, respectively, point to high mobility (high conductivity) and low recombination rate of photo‐generated charge carriers in α– and β–SrZrS3 materials, which are necessary for efficient photovoltaic conversion.
关键词： Solar cell,Optoelectronic properties,Density Functional Theory,chalcogenide perovskites,earth–abundant materials
更新于2025-09-23 15:19:57
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Optoelectronic Impacts of Particle Size in Water-Dispersible Plasmonic Copper Selenide Nanoparticles
摘要： There is significant interest in earth-abundant plasmonic materials, but whether or not their performance can match or even surpass their noble metal counterparts remains to be established. An important step in determining the extent of their versatility is to understand basic aspects of their plasmonic features. In this work, we measure near-infrared plasmonic molar extinction coefficients of water-dispersible copper selenide nanoparticles of different diameters. Obtaining molar extinction coefficients of these materials has traditionally been challenging because particles could not be synthesized at size ranges that avoid convoluting factors such as carrier density anomalies, surface depletion, and quantum confinement effects. Here, we report a straightforward synthesis that can control particle diameter within a size range that mitigates these convolutions, and then use these materials to establish their molar extinction coefficients. Importantly, we determine that size-dependent increases in molar extinction coefficients are likely a result of increases only in scattering cross-section, much like their noble metal analogues. Further, we show that the size-dependent trends in molar extinction coefficient follow the trends predicted by Mie theory well. These results suggest a promising outlook for the future implementation of earth-abundant and alternative plasmonic technologies from this material class.
关键词： plasmonic materials,copper selenide nanoparticles,molar extinction coefficients,earth-abundant materials,Mie theory
更新于2025-09-19 17:13:59
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Towards highly efficient thin-film solar cells with a graded-bandgap CZTSSe layer
摘要： A coupled optoelectronic model was implemented along with the differential evolution algorithm to assess the efficacy of grading the bandgap of the Cu2ZnSn(SξSe1?ξ)4 (CZTSSe) layer for enhancing the power conversion efficiency of thin-film CZTSSe solar cells. Both linearly and sinusoidally graded bandgaps were examined, with the molybdenum backreflector in the solar cell being either planar or periodically corrugated. Whereas an optimally graded bandgap can dramatically enhance the efficiency, the effect of periodically corrugating the backreflector is modest at best. An efficiency of 21.74% is predicted with sinusoidal grading of a 870-nm-thick CZTSSe layer, in comparison to 12.6% efficiency achieved experimentally with a 2200-nm-thick homogeneous CZTSSe layer. High electron-hole-pair generation rates in the narrow-bandgap regions and a high open-circuit voltage due to a wider bandgap close to the front and rear faces of the CZTSSe layer are responsible for the high enhancement of efficiency.
关键词： optoelectronic optimization,Bandgap grading,thin-film solar cell,earth-abundant materials,CZTSSe solar cell
更新于2025-09-16 10:30:52
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Magnesium for Transient Photonics
摘要： Optical recon?gurability has enabled the realization of photonic devices that including modulators, sensors, and signal processors. Yet, most change in functionality, approaches to date require the application of power, which severely limits their usage in portable devices. We demonstrate the concept of transient photonics based on Mg, a burgeoning material for (nano)photonics. We realize dynamic Mg/MgO/Mg color pixels covering the entire sRGB gamut color spectrum, where all hues vanish completely in less than 10 min upon exposure to water at room temperature and neutral pH, ideal for encryption. This scalable thin-?lm architecture has a robust angular response, maintaining vivid colors up to 80 degrees of incidence. Our transient photonics approach using materials that are earth-abundant and CMOS-compatible opens the door for the implementation of recon?gurable devices with controlled responses in the UV?IR that can disappear without leaving any trace after stable operation, relevant for healthcare, defense, and energy applications.
关键词： color pixels,recon?gurability,earth-abundant materials for photonics,dynamic optical response,magnesium,transient photonics
更新于2025-09-09 09:28:46