Computational study of III-V direct-gap semiconductors for thermoradiative cell applications

We investigate the performance of thermoradiative (TR) cells using the III-V group of semiconductors, which include GaAs, GaSb, InAs, and InP, with the aim of determining their efficiency and finding the best TR cell materials among the III-V group. The TR cells generate electricity from thermal radiation, and their efficiency is influenced by several factors such as the bandgap, temperature difference, and absorption spectrum. To create a realistic model, we incorporate sub-bandgap and heat losses in our calculations and utilize density-functional theory to determine the energy gap and optical properties of each material. Our findings suggest that the effect of absorptivity on the material, especially when the sub-bandgap and heat losses are considered, can decrease the efficiency of TR cells. However, careful treatment of the absorptivity indicates that not all materials have the same trend of decrease in the TR cell efficiency when taking the loss mechanisms into account. We observe that GaSb exhibits the highest power density, while InP demonstrates the lowest one. Moreover, GaAs and InP exhibit relatively high efficiency without the sub-bandgap and heat losses, whereas InAs display lower efficiency without considering the losses, yet exhibit higher resistance to sub-bandgap and heat losses compared to the other materials, thus effectively becoming the best TR cell material in the III-V group of semiconductors

Electrically controllable exchange bias via interface magnetoelectric effect

Exchange bias is a unidirectional magnetic anisotropy that often arise from interfacial interaction of a ferromagnetic and antiferromagnetic layers. In this article, we show that a metallic layer with spin-orbit coupling can induces an exchange bias via an interface magnetoelectric effect. In linear response regime, the interface magnetoelectric effect is induced by spin-orbit couplings that arises from the broken symmetry of the system. Furthermore, we demonstrate that the exchange bias can be controlled by electric field.Comment: 4 pages, 3 figures, presented on Intermag 202

Theory of high energy optical conductivity and the role of oxygens in manganites

Recent experimental study reveals the optical conductivity of La$_{1-x}$Ca$_x$MnO$_3$ over a wide range of energy and the occurrence of spectral weight transfer as the system transforms from paramagnetic insulating to ferromagnetic metallic phase [Rusydi {\it et al.}, Phys. Rev. B {\bf 78}, 125110 (2008)]. We propose a model and calculation within the Dynamical Mean Field Theory to explain this phenomenon. We find the role of oxygens in mediating the hopping of electrons between manganeses as the key that determines the structures of the optical conductivity. In addition, by parametrizing the hopping integrals through magnetization, our result suggests a possible scenario that explains the occurrence of spectral weight transfer, in which the ferromagnatic ordering increases the rate of electron transfer from O$_{2p}$ orbitals to upper Mn$_{e_g}$ orbitals while simultaneously decreasing the rate of electron transfer from O$_{2p}$ orbitals to lower Mn$_{e_g}$orbitals, as temperature is varied across the ferromagnetic transition. With this scenario, our optical conductivity calculation shows very good quantitative agreement with the experimental data.Comment: 10 pages, 6 figures (accepted

Application of the detailed balance model to thermoradiative cells based on a p-type two-dimensional indium selenide semiconductor

Thermoradiative (TR) cells are energy conversion devices that convert low-temperature waste heat to electricity. TR cells work on the same principles as photovoltaics, but they produce a reverse bias voltage due to higher cell temperature than the environment temperature. Depending on the energy gap of the material, temperature difference would generate electrical energy by electron-hole pair recombination. In this work, we propose a two-dimensional (2D) InSe for applications in the TR cells. The electronic properties of 2D InSe are obtained by using first-principles calculations. Then, the calculated energy gap is used to estimate output power density and efficiency according to the Shockley-Queisser framework through a detailed balance model adapted with the TR cells. Using a heat source at  = 1000 K and the ambient temperature = 300 K, an ideal TR cell of 2D InSe at the maximum power point can achieve output power density and efficiency up to 0.061 W/m2 and 4.41%, respectively, with an energy gap of 1.43 eV. However, sub-bandgap and non-radiative losses will degenerate the cell's performance significantly

Application of the detailed balance model to thermoradiative cells based on a p-type two-dimensional indium selenide semiconductor

Thermoradiative (TR) cells are energy conversion devices that convert low-temperature waste heat to electricity. TR cells work on the same principles as photovoltaics, but they produce a reverse bias voltage due to higher cell temperature than the environment temperature. Depending on the energy gap of the material, temperature difference would generate electrical energy by electron-hole pair recombination. In this work, we propose a two-dimensional (2D) InSe for applications in the TR cells. The electronic properties of 2D InSe are obtained by using first-principles calculations. Then, the calculated energy gap is used to estimate output power density and efficiency according to the Shockley-Queisser framework through a detailed balance model adapted with the TR cells. Using a heat source at T_c = 1000 K and the ambient temperature T_a = 300 K, an ideal TR cell of 2D InSe at the maximum power point can achieve output power density and efficiency up to 0.061 W/m2 and 4.41%, respectively, with an energy gap of 1.43 eV. However, sub-bandgap and non-radiative losses will degenerate the cell's performance significantly