Comprehensive first-principles study of bulk, bilayer, and monolayer α-PtO2 properties

Abstract

Abstract We calculated the structural stability, electronic, optical, and thermoelectric properties for α-PtO2 structures (bulk, bilayer, and monolayer) via first-principles density functional theory calculations. The results show that there is good agreement between the calculated lattice parameters and the available experimental data for the bulk structure. The in-plane Young's modulus and Poisson's ratio were calculated in the harmonic elastic strain range, and the results show that the monolayer is harder than the bulk. GW0 calculations on top of a semi-local generalised gradient approximation for the exchange-correlation energy predicted that the bilayer, monolayer, and the bulk α-PtO2 are all semiconductors with indirect band gaps. The results reveal that the band gap increases from bulk to monolayer. Calculations of optical properties show that the monolayer can absorb up to 8% of incident radiation in the visible range, which is higher than the 2.3% for graphene of the same thickness. In contrast, the bulk absorbs 1.77%. Phonon calculations confirm that all structures are dynamically stable. To examine the lattice thermal conductivity, the Boltzmann transport equation calculations in conjunction with density functional theory were implemented. The in-plane calculated lattice thermal conductivity were 8.47 × 10−8Wm−1K−1 for bulk, 4.59 × 10−8Wm−1K−1 for bilayer and 1.06 × 10−8Wm−1K−1 per layer at 300 K. The obtained thermoelectric figure of merit (ZT) per layer were 0.11 for bulk, 0.62 for bilayer and 0.74 for monolayer, respectively. The investigation shows that the n-type in monolayer has the most promise for thermoelectric applications.