Effects of the number of layers on the vibrational, electronic and optical properties of alpha lead oxide

Abstract

We have investigated the effects of number of layers on the structural, vibrational, electronic and optical properties of α-PbO using first principles calculations. Our theoretical calculations have shown that four Raman active modes of α-PbO tend to red-shift from bulk to monolayer due to decreasing of force constants and increasing of bond lengths. It has been shown that while bulk and multilayer α-PbO have an indirect band gap, monolayer form has a direct band gap value of 2.59 eV. Although lead atoms have 5d states, spin-orbit coupling does not significantly affect the band structure of α-PbO. The computed cleavage energy value (0.67 J/m 2 ) confirms that monolayer PbO can be easily obtained from its bulk counterpart by exfoliation methods. In addition to the band structure, we also calculated the optical properties and absorbed photon flux J abs of α-PbO structures to investigate the possibility of solar absorption. Our calculations reveal that while monolayer and bilayer PbO have relatively larger band gaps and lower absorption coefficients, their J abs values are not ideal for solar absorption devices. In contrast, the multilayer and bulk phases of the α-PbOs show good overlap with the solar spectrum and yield high electrical current values. Our calculations have indicated that ultrathin films of α-PbO (such as 3nm thickness) could be excellent candidates for solar cells. We believe that our work can be utilized to improve electronic and optical devices based on lead oxide structures. arXiv:1809.07263v1 [cond-mat.mes-hall]

Janus Pt XnY2−n ( XErsan1, Ataca2 2020Phys. Rev. AppliedSelf Cite621180View full textAdd to dashboardCite

“…The effects of the number of layers in low-dimensional layered materials on the optoelectronic and magnetic properties are significant [65][66][67]; therefore, we investigated bilayers of the bare PtX 2 and Janus PtXY structures. For Janus PtXY bilayers, we consider three different stacking orders as AA, AB, and AC.…”

First-Principles Studies for Electronic Structure and Optical Properties of Strontium Doped β-Ga2O3

“…Gallium oxide (Ga 2 O 3 ) embraces five different kinds of polymorphism, such as α, β, γ, δ, and ε phase [1,2]. Other examples of metal oxide structures are lead oxide (Pb 2 O 3 ) [3], molybdenum dioxide (MoO 2 ) [4], aluminium oxide (Al 2 O 3 ) [5], and zirconium oxide (ZrO 2 ) [6], which have a variety of polymorph phase similar to Ga 2 O 3 . Among all of these polymorphs of gallium oxide, β-Ga 2 O 3 plays an essential role in ultrawide bandgap (UWBG) applications, with a bandgap energy of 4.8 eV between the valence band and conduction band [7,8].…”

Carbon Nitride Supported Lead Oxide Nanoparticles for Memristor Application: Charge-Transport Mechanism for Resistive Switching

“…For the low conduction state, within the region from −5 to +4.3 V, the device was followed by a Poole–Frenkel emission (PF) mechanism, ln ( I / V ) vs V 0.5 , J PF = q μ N C E exp­((− q (Φ T – ( qE /πε) 0.5 )/ KT ), where q is the electron charge, μ is the electron mobility, N C is the density of states, E is the electric field, J PF is the current density, Φ T is the electrons trap depth, K is Boltzmann’s constant, ε is the permittivity of the material, and T is the absolute temperature, and for the high conduction state (within the range from +4.3 to −3.6 V) the transport behavior of the device was followed by the Ohmic conduction mechanism, ln ( I ) vs ln ( V ), with the slop values of ∼0.96, for both sides, Figure A,B. For further mechanistic discussion, an estimated energy diagram has been proposed in Figure C. − The low conduction state was fitted with a Frenkel–Poole emission model where the charge carriers were moved forward by a trap-assisted electron transport process through an electrical insulator (carbon nitride), Figure D. The electrons are generally trapped in different localized states and then overcome due to the gradual increase of applied electric field and finally reache the conduction band of carbon nitride through a bulk-limited conduction process.…”