First-principles study on the effective masses of zinc-blend-derived Cu2Zn−IV−VI4 (IV = Sn, Ge, Si and VI = S, Se)

Liu, Heng-Rui; Chen, Shiyou; Zhai, Yingteng; Xiang, Hongjun; Gong, Xin; Wei, Su‐Huai

doi:10.1063/1.4759322

Cited by 80 publications

(52 citation statements)

References 31 publications

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“…Hence, using the data of ref. 54 we find the following values (in units of the free electron mass, m 0 ): m KS (CZGS) = 0.61, m SN (CZGS) = 0.48, m KS (CZTS) = 0.49 and m SN (CZTS) = 0.44, for the KS-CZGS, SN-CZGS, KS-CZTS and SN-CZTS phases, respectively.…”

Section: Resultsmentioning

confidence: 62%

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Magnetotransport and conductivity mechanisms in Cu2ZnSnxGe1−xS4 single crystals

Lähderanta

Hajdeu-Chicarosh

Guc

et al. 2018

Sci Rep

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Resistivity, ρ(T), and magnetoresistance (MR) are investigated in the Cu2ZnSnxGe1−xS4 single crystals, obtained by the chemical vapor transport method, between x = 0–0.70, in the temperature range of T ~ 50–300 K in pulsed magnetic field of B up to 20 T. The Mott variable-range hopping (VRH) conductivity is observed within broad temperature intervals, lying inside that of T ~ 80–180 K for different x. The nearest-neighbor hopping conductivity and the charge transfer, connected to activation of holes into the delocalized states of the acceptor band, are identified above and below the Mott VRH conduction domain, respectively. The microscopic electronic parameters, including width of the acceptor band, the localization radius and the density of the localized states at the Fermi level, as well as the acceptor concentration and the critical concentration of the metal-insulator transition, are obtained with the analysis of the ρ(T) and MR data. All the parameters above exhibit extremums near x = 0.13, which are attributable mainly to the transition from the stannite crystal structure at x = 0 to the kesterite-like structure near x = 0.13. The detailed analysis of the activation energy in the low-temperature interval permitted estimations of contributions from different crystal phases of the border compounds into the alloy structure at different compositions.

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Section: Resultsmentioning

confidence: 62%

“…Here, m t and m l is the transversal and the longitudinal effective mass components, respectively, of the holes in the upmost valence band, which have been predicted for CZTS and CZGeS with the first-principle calculations 54 . Hence, using the data of ref.…”

Section: Resultsmentioning

confidence: 96%

Magnetotransport and conductivity mechanisms in Cu2ZnSnxGe1−xS4 single crystals

Lähderanta

Hajdeu-Chicarosh

Guc

et al. 2018

Sci Rep

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“…Table I summarizes the values that we used. The bandgap was derived from the absorption edge of the IQE curve, the average effective masses of electrons and holes were taken from [17], the acceptor density and minority carrier lifetime in the absorber were measured [5], the minority carrier diffusion length was derived from the bias dependence of the IQE, the relative permittivity was taken from [18], the builtin potential was estimated as being slightly below the bandgap value, and the series and shunt resistance values were derived directly from the J-V curves of Fig. 4.…”

Section: Two-diode Simulationmentioning

confidence: 99%

Investigation of Properties Limiting Efficiency in Cu2ZnSnSe4-Based Solar Cells

Brammertz

Oueslati

Buffière

et al. 2015

IEEE J. Photovoltaics

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We have investigated different nonidealities in Cu 2 ZnSnSe 4 -CdS-ZnO solar cells with 9.7% conversion efficiency, in order to determine what is limiting the efficiency of these devices. Several nonidealities could be observed. A barrier of about 300 meV is present for electron flow at the absorber-buffer heterojunction leading to a strong crossover behavior between dark and illuminated current-voltage curves. In addition, a barrier of about 130 meV is present at the Mo-absorber contact, which could be reduced to 15 meV by inclusion of a TiN interlayer. Admittance spectroscopy results on the devices with the TiN backside contact show a defect level with an activation energy of 170 meV. Using all parameters extracted by the different characterization methods for simulations of the two-diode model including injection and recombination currents, we come to the conclusion that our devices are limited by the large recombination current in the depletion region. Potential fluctuations are present in the devices as well, but they do not seem to have a special degrading effect on the devices, besides a probable reduction in minority carrier lifetime through enhanced recombination through the band tail defects.

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“…Here, we approximate m as 0.2m e , the value calculated for CZTS [32]. We calculate the minority carrier mobility to be 26 cm 2 /Vs for the as-deposited Cu 2 SnS 3 , and 55 cm 2 /Vs for the annealed sample.…”

Section: Terahertz Spectroscopy Investigation Of Minority Carrier Tramentioning

confidence: 99%

Effects of Disorder on Carrier Transport inCu2SnS3

et al. 2015

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In recent years, further improvements in the efficiency of Cu2ZnSn(S,Se)4 photovoltaic devices have been hampered due to several materials issues, including cation disorder. Cu2SnS3 is a promising new absorber material that has attracted significant interest in recent years. However, similar to CZTS, Cu2SnS3 displays cation disorder. In this work, we develop synthetic techniques to control the disorder in Cu2SnS3 thin films. By manipulating the disorder in this material, we observe crystal structure changes and detect improvements in the majority carrier (hole) transport. However, when the minority carrier (electron) transport was investigated using optical pump terahertz probe spectroscopy, minimal differences were observed between the ordered and disordered Cu2SnS3. By combining these results with first-principles and Monte Carlo theoretical calculations, we are able to conclude that even ostensibly "ordered" Cu2SnS3 displays minority carrier transport properties corresponding to the disordered structure. The presence of extended planar defects in all samples, observed in TEM imaging, suggests that disorder is present even when it is not detectable using traditional structural characterization methods. The results of this study highlight some of the challenges to the further improvement of Cu2SnS3-based photovoltaics, and have implications for other disordered multinary semiconductors such as CZTS.

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First-principles study on the effective masses of zinc-blend-derived Cu2Zn−IV−VI4 (IV = Sn, Ge, Si and VI = S, Se)

Cited by 80 publications

References 31 publications

Magnetotransport and conductivity mechanisms in Cu2ZnSnxGe1−xS4 single crystals

Magnetotransport and conductivity mechanisms in Cu2ZnSnxGe1−xS4 single crystals

Investigation of Properties Limiting Efficiency in Cu<sub>2</sub>ZnSnSe<sub>4</sub>-Based Solar Cells

Effects of Disorder on Carrier Transport inCu2SnS3

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