• Title/Summary/Keyword: $Cu_2ZnSnS_4$

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Effects of Sputter Deposition Sequence and Sulfurization Process of Cu, Zn, Sn on Properties of Cu2ZnSnS4 Solar Cell Material (Cu, Zn, Sn의 스퍼터링 적층방법과 황화 열처리공정이 Cu2ZnSnS4 태양전지재료 특성에 미치는 효과)

  • Park, Nam-Kyu;Arepalli, Vinaya Kumar;Kim, Eui-Tae
    • Korean Journal of Materials Research
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    • v.23 no.6
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    • pp.304-308
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    • 2013
  • The effect of a sputter deposition sequence of Cu, Zn, and Sn metal layers on the properties of $Cu_2ZnSnS_4$ (CZTS) was systematically studied for solar cell applications. The set of Cu/Sn/Zn/Cu multi metal films was deposited on a Mo/$SiO_2$/Si wafer using dc sputtering. CZTS films were prepared through a sulfurization process of the Cu/Sn/Zn/Cu metal layers at $500^{\circ}C$ in a $H_2S$ gas environment. $H_2S$ (0.1%) gas of 200 standard cubic centimeters per minute was supplied in the cold-wall sulfurization reactor. The metal film prepared by one-cycle deposition of Cu(360 nm)/Sn(400 nm)/Zn(400 nm)/Cu(440 nm) had a relatively rough surface due to a well-developed columnar structure growth. A dense and smooth metal surface was achieved for two- or three-cycle deposition of Cu/Sn/Zn/Cu, in which each metal layer thickness was decreased to 200 nm. Moreover, the three-cycle deposition sample showed the best CZTS kesterite structures after 5 hr sulfurization treatment. The two- and three-cycle Cu/Sn/Zn/Cu samples showed high-efficient photoluminescence (PL) spectra after a 3 hr sulfurization treatment, wheres the one-cycle sample yielded poor PL efficiency. The PL spectra of the three-cycle sample showed a broad peak in the range of 700-1000 nm, peaked at 870 nm (1.425 eV). This result is in good agreement with the reported bandgap energy of CZTS.

The synthesis and properties of point defect structure of Cu2-XZnSnS4 (x=0.1, 0.2, and 0.3)

  • Bui D. Long;Le T. Bang
    • Advances in materials Research
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    • v.13 no.1
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    • pp.55-62
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    • 2024
  • Cu-based sulfides have recently emerged as promising thermoelectric (TE) materials due to their low cost, non-toxicity, and abundance. In this research, point defect structure of Cu2-xZnSnS4 (x=0.1, 0.2, 0.3) samples were synthesized by the mechanical alloying method. Mixed powders of Cu, Zn, Sn and S were milled using high energy ball milling at a rotation speed of 300 rpm in Ar atmosphere. The milled Cu2-xZnSnS4 powders were heat-treated at 723 K for 24 h, and subsequently consolidated using spark plasma sintering (SPS) under an applied pressure of 60 MPa for 15 min. The thermal conductivity of the sintered Cu2-xZnSnS4 samples was evaluated. A well-defined Cu2-xZnSnS4 powders were successfully formed after milling for 16 h, with the particle sizes mostly distributed in the range of 60-100 nm. The lattice constants of aand cdecreased with increasing composition value x. The thermal conductivity of sintered x=0.1 sample exhibited the lowest value and attained 0.93 W/m K at 673 K.

Characterization of Cu2ZnSnSe4 Thin Films Selenized with Cu2-xSe/SnSe2/ZnSe and Cu/SnSe2/ZnSe Stacks

  • Munir, Rahim;Jung, Gwang Sun;Ko, Young Min;Ahn, Byung Tae
    • Korean Journal of Materials Research
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    • v.23 no.3
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    • pp.183-189
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    • 2013
  • $Cu_2ZnSn(S,Se)_4$ material is receiving an increased amount of attention for solar cell applications as an absorber layer because it consists of inexpensive and abundant materials (Zn and Sn) instead of the expensive and rare materials (In and Ga) in $Cu(In,Ga)Se_2$ solar cells. We were able to achieve a cell conversion efficiency to 4.7% by the selenization of a stacked metal precursor with the Cu/(Zn + Sn)/Mo/glass structure. However, the selenization of the metal precursor results in large voids at the absorber/Mo interface because metals diffuse out through the top CZTSe layer. To avoid the voids at the absorber/Mo interface, binary selenide compounds of ZnSe and $SnSe_2$ were employed as a precursor instead of Zn and Sn metals. It was found that the precursor with Cu/$SnSe_2$/ZnSe stack provided a uniform film with larger grains compared to that with $Cu_2Se/SnSe_2$/ZnSe stack. Also, voids were not observed at the $Cu_2ZnSnSe_4$/Mo interface. A severe loss of Sn was observed after a high-temperature annealing process, suggesting that selenization in this case should be performed in a closed system with a uniform temperature in a $SnSe_2$ environment. However, in the experiments, Cu top-layer stack had more of an effect on reducing Sn loss compared to $Cu_2Se$ top-layer stack.

Effect of Pre-annealing on the Formation of Cu2ZnSn(S,Se)4 Thin Films from a Se-containing Cu/SnSe2/ZnSe2 Precursor

  • Ko, Young Min;Kim, Sung Tae;Ko, Jae Hyuck;Ahn, Byung Tae;Chalapathy, R.B.V.
    • Current Photovoltaic Research
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    • v.10 no.2
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    • pp.39-48
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    • 2022
  • A Se-containing Cu/SnSe2/ZnSe precursor was employed to introduce S to the precursor to form Cu2ZnSn(S,Se)4 (CZTSSe) film. The morphology of CZTSSe films strongly varied with two different pre-annealing environments: S and N2. The CZTSSe film with S pre-annealing showed a dense morphology with a smooth surface, while that with N2 pre-annealing showed a porous film with a plate-shaped grains on the surface. CuS and Cu2Sn(S,Se)3 phases formed during the S pre-annealing stage, while SnSe and Cu2SnSe3 phases formed during the N2 pre-annealing stage. The SnSe phase formed during N2 pre-annealing generated SnS2 phase that had plate shape and severely aggravated the morphology of CZTSSe film. The power conversion efficiency of the CZTSSe solar cell with S pre-annealing was low (1.9%) due to existence of Zn(S.Se) layer between CZTSSe and Mo substrate. The results indicated that S pre-annealing of the precursor was a promising method to achieve a good morphology for large area application.

Characterization and deposition of Cu2ZnSnS4 film for thin solar cells via sol-gel method (Sol-gel법에 의한 박막태양전지용 Cu2ZnSnS4 박막의 증착과 특성)

  • Kim, Gwan-Tae;Lee, Sang-Hyun;Park, Byung-Ok
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.22 no.3
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    • pp.127-133
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    • 2012
  • To achieve low-cost and high-efficiency of thin-film solar cells applications, the sol-gel method that can be coated on a large area substrate, obtain homogeneous thin films of high purity was used. We studied structural and optical characteristics versus annealing temperature of $Cu_2ZnSnS_4$ which has kesterite structure by substitution low-cost sulfur (S) instead of high-cost selenium (Se). By analyzing XRD patterns, main peak was observed at $2{\theta}=28.5^{\circ}$ when Zn/Sn ratio is 0.8/1.2. And when we observed kesterite structure which has orientation of (112) direction, the more annealing temperature increase the bigger strength of (112) direction is. $Cu_2ZnSnS_4$ thin film showed characteristics of kesterite structure at $550^{\circ}C$. And when we calculated lattice constant, a = 5.5047 and $c=11.014{\AA}$ as same JCPDS (Joint Committee on Powder Standards) data measured. We measured optical transmittance to analyze optical characteristics. Optical transmittance was lower than 65 % at visible ray (${\lambda}=380{\sim}770nm$).

Fabrication of Cu2ZnSnS4 Films by Rapid Thermal Annealing of Cu/ZnSn/Cu Precursor Layer and Their Application to Solar Cells

  • Chalapathy, R.B.V.;Jung, Gwang Sun;Ko, Young Min;Ahn, Byung Tae;Kwon, HyukSang
    • Current Photovoltaic Research
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    • v.1 no.2
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    • pp.82-89
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    • 2013
  • $Cu_2ZnSnS_4$ thin film have been fabricated by rapid thermal annealing of dc-sputtered metal precursor with Cu/ZnSn/Cu stack in sulfur ambient. A CZTS film with a good uniformity was formed at $560^{\circ}C$ in 6 min. $Cu_2SnS_3$ and $Cu_3SnS_4$ secondary phases were present at $540^{\circ}C$ and a trace amount of $Cu_2SnS_3$ secondary phase was present at $560^{\circ}C$. Single-phase large-grained CZTS film with rough surface was formed at $560^{\circ}C$. Solar cell with best efficiency of 4.7% ($V_{oc}=632mV$, $j_{sc}=15.8mA/cm^2$, FF = 47.13%) for an area of $0.44cm^2$ was obtained for the CZTS absorber grown at $560^{\circ}C$ for 6 min. The existence of second phase at lower-temperature annealing and rough surface at higher-temperature annealing caused the degradation of cell performance. Also poor back contact by void formation deteriorated cell performance. The fill factor was below 0.5; it should be increased by minimizing voids at the CZTS/Mo interface. Our results suggest that CZTS absorbers can be grown by rapid thermal annealing of metallic precursors in sulfur ambient for short process times ranging in minutes.

Fabrication of a Cu2ZnSn(S,Se)4 thin film solar cell with 9.24% efficiency from a sputtered metallic precursor by using S and Se pellets

  • Gang, Myeong-Gil;Hong, Chang-U;Yun, Jae-Ho;Gwak, Ji-Hye;An, Seung-Gyu;Mun, Jong-Ha;Kim, Jin-Hyeok
    • Proceedings of the Korean Vacuum Society Conference
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    • 2015.08a
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    • pp.86.2-86.2
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    • 2015
  • Cu2ZnSn(S,Se)4 thin film solar cells have been fabricated using sputtered Cu/Sn/Zn metallic precursors on Mo coated sodalime glass substrate without using a toxic H2Se and H2S atmosphere. Cu/Sn/Zn metallic precursors with various thicknesses were prepared using DC magnetron sputtering process at room temperature. As-deposited metallic precursors were sulfo-selenized inside a graphite box containing S and Se pellets using rapid thermal processing furnace at various sulfur to selenium (S/Se) compositional ratio. Thin film solar cells were fabricated after sulfo-selenization process using a 65 nm CdS buffer, a 40 nm intrinsic ZnO, a 400 nm Al doped ZnO, and Al/Ni top metal contact. Effects of sulfur to selenium (S/Se) compositional ratio on the microstructure, crystallinity, electrical properties, and cell efficiencies have been studied using X-ray diffraction, Raman spectroscopy, field emission scanning electron microscope, I-V measurement system, solar simulator, quantum efficiency measurement system, and time resolved photoluminescence spectrometer. Our fabricated Cu2ZnSn(S,Se)4 thin film solar cell shows the best conversion efficiency of 9.24 % (Voc : 454.6 mV, Jsc : 32.14 mA/cm2, FF : 63.29 %, and active area : 0.433 cm2), which is the highest efficiency among Cu2ZnSn(S,Se)4 thin film solar cells prepared using sputter deposited metallic precursors and without using a toxic H2Se gas. Details about other experimental results will be discussed during the presentation.

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Study on Indium-free and Indium-reduced thin film solar absorber materials for photovoltaic application

  • Wibowo, Rachmat Adhi;Kim, Gyu-Ho
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.11a
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    • pp.270-273
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    • 2007
  • In this report, Indium-free and Indium-reduced thin film materials for solar absorber were studied in order to search alternative materials for thin film solar cell. The films of $Cu_2ZnSnSe_4$ and $Cu_2ZnSnSe_2$ were deposited using mixed binary chalcogenides powders. From the film bulk analysis result, it is observed that Cu concentration is a function of substrate temperature as well as CuSe mole ratio in the target. Under optimized conditions, $Cu_2ZnSnSe_4$ and $Cu_2ZnSnSe_2$ thin films grow with strong (112), (220/204) and (312/116) reflections. Films are found to exhibit a high absorption coefficient of $10^4$ $cm^{-1}$. $Cu_2ZnSnSe_4$ film shows a 1.5 eV band gap. On the other side, an increasing of optical band gap from 1.0 eV to 1.25 eV ($CuInSnSe_2$) is found to be proportional with an increasing of Zn concentration. All films have a p-type semiconductor characteristic with a carrier concentration in the order of $10^{14}$ $cm^{-3}$, a mobility about $10^1$ $cm^{2{\cdot}-1.}S^{-1}$ and a resistivity at the range of $10^2-10^6$ ${\Omega}{\cdot}m$.

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Characterization of $Cu_2ZnSnSe_4$ thin film produced by selenization of metallic precursor (금속 프리커서의 셀렌화에 의한 $Cu_2ZnSnSe_4$ 박막의 특성)

  • Amal, M. Ikhlasul;Alfaruqy, M. Hilmy;Jang, Yun-Jung;Kim, Kyoo Ho
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.85.2-85.2
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    • 2010
  • $Cu_2ZnSnSe_4$ (CZTSe) is one of candidate to alternate $Cu(In,Ga)Se_2$ as solar absorber material for solar cell. The expensive elements of In and Ga are replaced by Zn and Sn, respectively to lower the material cost. In this study we fabricated CZTSe thin film by selenization of single precursor layer consisted metallic constituent. Precursor compositions ratio were selected to have Cu-poor and Zn-rich content and prepared by RF magnetron sputtering. Thermal processing was applied to introduce selenium into as-deposited films at temperatures ranging from 350 to 500 for time up to 120 minutes. Single precursor films showed amorphous structure and consist of individual elements of Cu, Zn, and Sn. It was confirmed by XRD analysis that synthesis of CZTSe compound is occurred from lower temperature process, although concurrently additional phases such as binary cooper selenides are also existed. The quality of CZTSe crystal was improved as temperature increased. We also investigated the optical and electrical properties of as-selenized CZTSe as well.

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Characterization of the Cu-layer deposition time on Cu2ZnSnS4 (CZTS) Thin Film Solar Cells Fabricated by Electro-deposition (Cu층 증착시간에 따른 Cu2ZnSnS4 (CZTS) 박막의 특성)

  • Kim, Yoon Jin;Kim, In Young;Gang, Myeng Gil;Moon, Jong Ha;Kim, Jin Hyeok
    • Current Photovoltaic Research
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    • v.4 no.1
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    • pp.16-20
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    • 2016
  • $Cu_2ZnSnS_4$ (CZTS) thin films were fabricated by successive electrodeposition of layers of precursor elements followed by sulfurization of an electrodeposited Cu-Zn-Sn precursor. In order to improve quality of the CZTS films, we tried to optimize the deposition condition of absorber layers. In particular, I have conducted optimization experiments by changing the Cu-layer deposition time. The CZTS absorber layers were synthesized by different Cu-layer conditions ranging from 10 to 16 minutes. The sulfurization of Cu/Sn/Zn stacked metallic precursor thin films has been conducted in a graphite box using rapid thermal annealing (RTA). The structural, morphological, compositional, and optical properties of CZTS thin films were investigated using X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and X-ray Flourescenece Spectrometry (XRF). Especially, the CZTS TFSCs exhibits the best power conversion efficiency of 4.62% with $V_{oc}$ of 570 mV, $J_{sc}$ of $18.15mA/cm^2$ and FF of 45%. As the time of deposition of the Cu-layer to increasing, the properties were confirmed to be systematically changed. And we have been discussed in detail below.