Computational Envision of Structural, Electronic, Mechanical and Thermoelectric Properties of PdXSn (X=Zr, Hf) half Heusler compounds

Half heusler compounds have gained attention due to their excellent properties and good thermal stability. In this paper, using first principle calculation and Boltzmann transport equation, we have investigated structural, electronic, mechanical and thermoelectric properties of PdXSn (X=Zr,Hf) half Heusler materials. These materials are indirect band gap semiconductors with band gap of 0.52 (0.44) for PdZrSn (PdHfSn). Calculations of elastic and phonon characteristics show that both materials are mechanically and dynamically stable. At 300K the magnitude of lattice thermal conductivity observed for PdZrSn is 15.16 W/mK and 9.53 W/mK for PdHfSn. The highest ZT value for PdZrSn and PdHfSn is 0.32 and 0.4 respectively.

Deep level transient spectroscopy and photoluminescence studies of hole and electron traps in ZnSnP2 bulk crystals

ZnSnP2, an emerging inorganic material for solar cells, was characterized by deep level transient spectroscopy (DLTS) and photoluminescence (PL). Acceptor- and donor-like traps with shallow energy levels were detected by DLTS analysis. The previous study based on first-principle calculation also suggested such traps were due to antisite defects of Zn and Sn. PL measurements also revealed sub-gap transitions related to these trap levels. Additionally, DLTS found a trap with deep level in ZnSnP2. A short lifetime of minority carrier in previous work might be due to such trap, coming from phosphorus vacancies and/or zinc interstitials suggested by first-principle study.

Electronic structure and Thermoelectric Properties of Hybrid Organic-Inorganic Perovskites [NH3-(CH2)3-COOH]2CdCl4

In this work, we conducted the first principle calculation of electronic structure and transport properties of [NH3-(CH2)3-COOH]2CdCl4 (Acid-Cd). The generalized gradient approximation is used in structural optimization and electronic structure. The theoretical band gap value found is in good agreement with experimental. Electronic thermal conductivity, electrical conductivity, Seebeck coefficient (S) and figure of merit (ZT) have been calculated using semi-local Boltzmann theory to predict the thermoelectric characteristic of the studied materials.

First-Principle Study on p-n Control of PEDOT-Based Thermoelectric Materials by PTSA Doping

PEDOT:Tos, a PSS-free PEDOT-based material, is a promising possible organic thermoelectric material for a practical conversion module because the material reportedly has a large power factor. However, since PEDOT:Tos is mainly reported to be a p-type thermoelectric material, the development of PSS-free PEDOT with n-type thermoelectric properties is desirable. Thus, in order to search for PSS-free PEDOT with n-type thermoelectric properties, we investigated the doping concentration of PTSA dependence of the thermoelectric property using the first-principle calculation. The band structure and the density of state indicated that the n-type thermal electromotive force was attributed to the electrons’ large effective mass. Such electrons were produced thanks to the binding of the dopant PTSA to the benzene ring. The contribution of the electron to the Seebeck coefficient increased with increasing PTSA doping concentrations.

Computational Revolutions in Lattice Thermal Conductivity

Understanding and controlling the phonon, the dominant heat carrier of semiconductor materials, is essential to developing a wide variety of applications. This article studies the theoretical and computational approach of the calculation of lattice thermal conductivity of semiconducting materials. Despite having different methods to calculate the lattice thermal conductivity, first-principle estimates predict more accurately in most applications. This motivates to present the descriptive explanation on first-principle calculation with the combination of lattice dynamics and Boltzmann transport equation. Finally, we summarized an overview of the recent achievements and opportunities.