How small amounts of Ge modify the formation pathways and crystallization of kesterites

Giraldo, Sergio; Saucedo, Edgardo; Neuschitzer, Markus; Oliva, Florian; Placidi, Marcel; Alcobé, Xavier; Izquierdo-Roca, Víctor; Kim, Shinho; Tampo, Hitoshi; Shibata, Hajime; Pérez-Rodrı́guez, A.; Pistor, Paul

doi:10.1039/c7ee02318a

Cited by 187 publications

(208 citation statements)

References 39 publications

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“…2(c) as no such bottom FG layers are obtained in carbon free techniques. [20][21][22] The small network of grain boundaries in the FG layer may contribute high series resistance and reduce the fill factor of solar cells. 11,23,24) It is difficult to draw conclusions about the total thickness of the entire film due to the combination of uncertainty in the precursor thickness (nominally 1.0 ± 0.1 µm) and surface roughness however, it can be clearly seen that as the thickness of the FG layer increases, the MoSe 2 layer becomes thinner.…”

Section: Resultsmentioning

confidence: 99%

Enhanced external quantum efficiency from Cu₂ZnSn(S,Se)₄ solar cells prepared from nanoparticle inks

Qu¹,

Zoppi²,

Peter³

et al. 2018

Jpn. J. Appl. Phys.

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Cu2ZnSn(S,Se)4 (CZTSSe) thin film photovoltaic absorber layers are fabricated by selenizing Cu2ZnSnS4 (CZTS) nanoparticle thin films in a selenium rich atmosphere. The selenium vapor pressure is controlled to optimize the morphology and quality of the CZTSSe thin film. The largest grains are formed at the highest selenium vapor pressure of 226 mbar. Integrating this photovoltaic absorber layer in a conventional thin film solar cell structure yields a champion short circuit current of 37.9 mA/cm2 without an antireflection coating. This stems from an improved external quantum efficiency characteristic in the visible and near-infrared part of the solar spectrum. The physical basis of this improvement is qualitatively attributed to a substantial increase in the minority carrier diffusion length.

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Section: Resultsmentioning

confidence: 99%

Enhanced external quantum efficiency from Cu₂ZnSn(S,Se)₄ solar cells prepared from nanoparticle inks

Qu¹,

Zoppi²,

Peter³

et al. 2018

Jpn. J. Appl. Phys.

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“…Different stages have been overcame, and the recent one is based on a partial substitution of different cations in the standard Cu 2 ZnSnS 4 (CZTS) compound 1–4 . This approach was found to lead to a substantial decrease of the detrimental defects in CZTS, increasing the device efficiency 1–4 . One of the most discussed elements to be add in CZTS is germanium, replacing partially tin.…”

Section: Introductionmentioning

confidence: 99%

“…One of the most discussed elements to be add in CZTS is germanium, replacing partially tin. In this framework, several papers demonstrating a positive Ge effect on the solar cell efficiency have appeared recently 4–8 . In addition, the Cu 2 ZnSn x Ge 1−x S 4 (CZTGS) solid solutions exhibit an increase of the band gap, E g , with increasing Ge concentration, reaching the values of E g up to ~2.3 eV for the pure Cu 2 ZnGeS 4 (CZGS) compound 9,10 .…”

Section: Introductionmentioning

confidence: 99%

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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“…Currently, the certified highest efficiency (12.6%) has been achieved using hydrazine‐based solution approach, although the wide variety of deposition techniques, like coevaporation, sputtering, spray, spin‐coating, or doctor‐blade coating, have also given efficiencies above 10%.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, the available literature on kesterites show that the sputtering is the most widely used PVD‐based technique. In this field, IMEC and Nankai University both have reported 10.4% efficiencies for pure selenium CZTSe devices, while IREC and Solar Frontier both have achieved 11.8% efficiency for CZTSe and CZTSSe respectively, DGIST has reported a 12.3% efficiency CZTSSe device, and the UNSW has reported a certified 11.0% efficiency cell for pure sulfur CZTS …”

Section: Introductionmentioning

confidence: 99%

Study and optimization of alternative MBE‐deposited metallic precursors for highly efficient kesterite CZTSe:Ge solar cells

Giraldo

Kim

Andrade‐Arvizu

et al. 2019

Progress in Photovoltaics

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Nowadays, most of the best efficiencies of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells are obtained from absorber layers fabricated using sequential processes, including the deposition of metallic stack precursors, typically by sputtering, and followed by reactive annealing under chalcogen atmosphere. The sputtering technique is widely known for the easy growth of metallic layers, although the deposition rates, growth morphology and nucleation, or the roughness can sometimes be an issue leading to inhomogeneities in the final layers. Nevertheless, MBE (molecular beam epitaxy) technique could have some advantages to obtain high‐quality metallic layers, with accurate control of the growth due to ultra‐high vacuum conditions and high purity. In this work, we study the use of advanced MBE systems to grow metallic stack precursors, alternatively to sputtering or thermal evaporation techniques, to obtain high‐quality CZTSe:Ge absorbers. Due to differences in the nature of each type of precursor, thermal annealing optimizations are presented by modifying some critical selenization parameters, such as the temperature or the selenium amount in order to obtain well‐crystallized absorbers. Detailed morphological, compositional, and structural characterizations show relevant features of each precursor, mainly related to the formation of MoSe2 at the back interface, and Se and Sn composition after selenization in different conditions. Regarding the solar cell devices, main efficiency limitations come from VOC and FF, which could be tentatively related to a noncontrolled selenization; different precursor reactivity, porosity, or composition; and different alkali diffusion during the reactive annealing. Finally, in the first optimization, a 9.2% efficiency device has been achieved with promising perspectives for future improvements.

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How small amounts of Ge modify the formation pathways and crystallization of kesterites

Abstract: A fundamental analysis of the impact of Ge on the synthesis of Cu2ZnSnSe4:Ge by a sequential process is presented, reporting the consequences on the absorber morphology and solar cell devices performance.

Cited by 187 publications

References 39 publications

Enhanced external quantum efficiency from Cu₂ZnSn(S,Se)₄ solar cells prepared from nanoparticle inks

Enhanced external quantum efficiency from Cu₂ZnSn(S,Se)₄ solar cells prepared from nanoparticle inks

Magnetotransport and conductivity mechanisms in Cu2ZnSnxGe1−xS4 single crystals

Study and optimization of alternative MBE‐deposited metallic precursors for highly efficient kesterite CZTSe:Ge solar cells

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How small amounts of Ge modify the formation pathways and crystallization of kesterites

Abstract: A fundamental analysis of the impact of Ge on the synthesis of Cu2ZnSnSe4:Ge by a sequential process is presented, reporting the consequences on the absorber morphology and solar cell devices performance.

Cited by 187 publications

References 39 publications

Enhanced external quantum efficiency from Cu2ZnSn(S,Se)4 solar cells prepared from nanoparticle inks

Enhanced external quantum efficiency from Cu2ZnSn(S,Se)4 solar cells prepared from nanoparticle inks

Magnetotransport and conductivity mechanisms in Cu2ZnSnxGe1−xS4 single crystals

Study and optimization of alternative MBE‐deposited metallic precursors for highly efficient kesterite CZTSe:Ge solar cells

Contact Info

Product

Resources

About

Enhanced external quantum efficiency from Cu₂ZnSn(S,Se)₄ solar cells prepared from nanoparticle inks

Enhanced external quantum efficiency from Cu₂ZnSn(S,Se)₄ solar cells prepared from nanoparticle inks