• Title, Summary, Keyword: Precursor

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Effect of Preparation Condition of Precursor Thin Films on the Properties of CZTS Solar Cells

  • Seong, Si-Jun;Park, Si-Nae;Kim, Dae-Hwan;Gang, Jin-Gyu
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.318.1-318.1
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    • 2013
  • Nowadays Cu2ZnSnS4 (CZTS) solar cell is attracting a lot of attention as a strong alternative to CIGS solar cell due to nontoxic and inexpensive constituent elements of CZTS. From various processes for the fabrication of CZTS solar cell, solution-based deposition of CZTS thin films is well-known non-vacuum process and many researchers are focusing on this method because of large-area deposition, high-throughput, and efficient material usage. Typically the solution-based process consists of two steps, coating of precursor solution and annealing of the precursor thin films. Unlike vacuum-based deposition, precursor solution contains unnecessary elements except Cu, Zn, Sn, and S in order to form high quality precursor thin films, and thus the precise control of precursor thin film preparation is essential for achieving high efficient CZTS solar cells. In this work, we have investigated the effect of preparation condition of CZTS precursor thin films on the performance of CZTS solar cells. The composition of CZTS precursor solution was controlled for obtaining optimized chemical composition of CZTS absorber layers for high-efficiency solar cells. Pre-annealing process of the CZTS precursor thin films was also investigated to confirm the effect of thermal treatment on chemical composition and carbon residues of CZTS absorber layers. The change of the morphology of CZTS precursor thin film by the preparation condition was also observed.

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Yield enhancement of matrix precursor in short carbon fiber reinforced randomly oriented carbon/carbon composite

  • Raunija, Thakur Sudesh Kumar;Sharma, Sharad Chandra;Verma, Anil
    • Carbon letters
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    • v.19
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    • pp.57-65
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    • 2016
  • Isroaniso matrix precursor synthesized from commercially available petroleum pitch was stabilized in air. The influence of oxygen mass gain during stabilization on the yield of matrix precursor was studied. Additionally, the influence of pressure on the yield of the stabilized matrix precursor in a real system was studied. The fourier transform infrared spectrometry (FTIR), thermogravimetric analysis (TGA), yield, yield rate, and yield impact were used to check the effect of stabilization and pressure on the yield of the matrix precursor and the end properties of the composite thereafter. The results showed that the yield increased with stabilization duration up to 20 h whereas it decreased for stabilization duration beyond 20 h. Further results showed that the stabilized matrix precursor for a duration of 5 h could withstand almost two-fold greater hot-pressing pressure without resulting in exudation as compared to that of a 1 h stabilized matrix precursor. The enhanced hot-pressing pressure significantly improved the yield of the matrix precursor. As a consequence, the densification and mechanical properties were increased significantly. Further, the matrix precursor stabilized for a duration of 20 h or more failed to provide proper and uniform binding of the reinforcement.

Fabrication of Al 6061 Foamable Precursor by Powder Metallurgical and Induction Heating Method (P/M법과 유도가열 공정을 이용한 발포용 6061 Al 합금 프리커서 제조)

  • 윤성원;강충길
    • Transactions of Materials Processing
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    • v.12 no.5
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    • pp.457-464
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    • 2003
  • In the powder compact melting technique, proper precursor fabrication is very important because density distribution after foaming and foamability are determined during precursor fabrication process. The fabrication of the precursor has to be performed very carefully because any residual porosity or other defects will lead to poor results in further processing. In order to evaluate the effect of the compaction parameters on the kinetics of the foaming process, a series of experiments were performed. In this study, aluminium foams with a closed cell structure were fabricated by using both the powder compact method and the induction heating process. A proper induction coil was designed to obtain a uniform temperature distribution over the entire cross sectional area of precursor. To establish the foamable precursor fabrication conditions, effects of process parameters such as the titanium hydride content (0.3∼1.5 wt.%), pressing pressure of the foamable precursor (50∼150kN) on the pore morphology were investigated.

Co-evaporator를 이용하여 제작한 CIGS Precursor Stack 구조 및 RTP 조건에 따른 Selenization 효과에 관한 연구

  • Kim, Chan;Kim, Dae-Hwan;Seong, Si-Jun;Gang, Jin-Gyu;Lee, Il-Su;Do, Jin-Yeong;Park, Wan-U
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.404-405
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    • 2011
  • Cu(InGa)$Se_2$ (CIGS) 박막 태양전지의 저가 및 대면적화를 위한 양산화 공정인 two-step process (sputter/selenization) 공정에서는 sputtering으로 형성한 metal precursor stack을 $H_2$ Se gas를 이용하여 selenization하는 공정을 주로 이용한다. 하지만 이러한 selenization 공정은 유독한 $H_2$ Se gas를 이용해야 한다는 점과 긴 시간 동안 열처리를 해야 하는 단점을 가지고 있다. 이에 metal precursor stack 위에 Se 막을 우선 증착하고, Rapid Thermal Process (RTP)를 이용하여 selenization하는 방법이 현재 많은 관심을 끌고 있다. 본 논문에서는 sputtering 이후 RTP를 이용한 CIGS 흡수층 제작에 대한 선행연구의 일환으로 co-evaporator 장비를 이용하여 다양한 구조의 precursor를 제작하고 RTP 조건에 따른 selenization 효과를 연구하였다. Co-evaporator를 이용하여 CIGS, CIG/Se, CuGa/In/Se, In/CuGa/Se 4가지 구조의 precursor stack을 Mo coated soda lime glass 위에 제작하였다. 이때 amorphous 상태의 precursor stack을 만들기 위하여 기판에 열은 가하여 주지 않았으며, 각각의 stack 구조에서 가지고 있는 Cu, In, Ga, Se의 총량을 동일하게 유지하기 위하여 각 stack의 증착 시간을 동일하게 유지하였다. Selenization을 위한 RTP 조건은 550, $600^{\circ}C$ 각각에 대하여 1, 5, 10분으로 split을 진행하였다. Precursor stack의 증착 후 관찰한 XRD 결과는 비정질 상태를 잘 나타내었으며, SEM 결과 CIGS precursor stack을 제외한 나머지 구조의 stack에서는 In 박막의 surface roughness로 인하여 박막의 평탄화가 좋지 않음을 확인하였다. CIGS precursor stack의 경우, RTP 온도와 시간 split와 상관없이 결정화가 잘 이루어졌으나 grain의 성장이 부족하였다. 이에 비하여 CIG/Se, CuGa/In/Se, In/CuGa/Se 구조의 precursor stack의 경우, $550^{\circ}C$ 열처리에서는 InSe의 결정상이 관찰 되었으며 $600^{\circ}C$, 5분 이상 열처리에서 CIGS 결정상이 관찰되었다. 이러한 결과는 Se이 metal 원소들과 함께 있는 CIGS 구조에 비하여 metal precursor stack 위에 Se을 증착한 stack 구조들의 경우는 CIGS 결정을 형성하기 위해 Se이 metal 층들로 확산되어 반응을 하여야 하므로 상대적으로 많은 열에너지가 필요한 것으로 이해할 수 있으며, RTP를 이용한 selenization 공정으로 CIGS 박막 태양전지의 흡수층 형성이 가능함을 확인하였다.

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Development of Thermal Precursor DB for Partial Disconnection and Poor Contact on Electrical Wire (배선에서의 반단선 및 접촉불량에 대한 열적 전조 DB구축)

  • Kim, Doo-Hyun;Kim, Sung-Chul;Lee, Jong-Ho;Kang, Dong-Kyu
    • Journal of the Korean Society of Safety
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    • v.24 no.2
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    • pp.30-36
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    • 2009
  • This paper aims at the precursor analysis and DB development of electrical fires based on thermal and current signals for partial disconnection and poor contact on electric wires through experiments and simulations. Also, DB system required for developing the precursor DB with these data was studied and designed. Firstly, in case of partial disconnection, characteristics were derived and analyzed by experiment and electrical-thermal finite element method(Flux 3D) on the model wires which consist of VCTF and IV electric wires. Based on the characteristics, About 351 partial disconnection precursor patterns were generated by the thermal analysis for electric wire according to deterioration time under normal state and 200% overload state of rated current. Secondly, in order to develop poor contact precursor patterns, temperature value and the current signal were considered. In simulating the poor contact situation on connector area of MCCB, connection torque was changed. Through the experimental analysis, about 251 poor contact precursor patterns were generated. Finally, Using thermal precursor patterns obtained by partial disconnection and poor contact, electrical fire thermal precursor DB was developed.

Fabrication of fine BSCCO-2223 precursor powder by spray pyrolysis process (분무 열분해방법에 의한 미세 BSCCO-2223 전구분말의 제조)

  • 김성환;유재무;고재웅;김영국;박기호
    • Progress in Superconductivity
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    • v.5 no.1
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    • pp.65-69
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    • 2003
  • Many researches on fabrication process for BSCCO precursor powders have been developed for high J$_{c}$ BSCCO-2223 tape. Spray pyrolysis method for fabrication of precursor powder has many advantages, such as high purity, fine particle size and low carbon content of BSCCO precursor powder. Fine, spherical powders were prepared by ultrasonic spray pyrolysis from the aqueous solution of metal nitrates. BSCCO precursor powders were synthesized with various solutes concentration and heat treatment conditions. Average particle size for spray pyrolysis powders was $1.5∼3\mu\textrm{m}$. Bi-2223/Ag tape was prepared by PIT method and followed by various sintering conditions. BSCCO precursor powders were characterized by XRD, SEM, EDS, Carbon content and particle size analysis.s.

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High textured carbon from chemical vapor infiltration with ethanol precursor and its rate of pyrolytic carbon deposition

  • Choi, Si Won;Joo, Kyung Do;Chung, Gui-Yung
    • Korean Journal of Chemical Engineering
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    • v.34 no.10
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    • pp.2764-2772
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    • 2017
  • Preparation of C/C composites with ethanol precursor was studied and the role of ethanol in obtaining high textured (HT) carbon was confirmed. HT carbon was obtained more with ethanol precursor than with propane precursor as reported by Ren et al. The pyrolytic carbon deposition rate constant from ethanol precursor, which has never been reported before in any other research, was obtained. It was confirmed that a proper mixture precursor of ethanol and propane could be used in the process of temperature gradient chemical vapor infiltration (TG-CVI) on behalf of the uniform deposition throughout the preform and the deposition with more HT carbon,. The pyrolytic carbon deposition rate constant for the CVI with propane precursor obtained in this research was 2.2-times greater than that reported by Vaidyaraman.

Properties of Precursor Pitch Derived from Petroleum Residue

  • Yu, Hae-Il;Lee, Gyu-Dong;Gwon, Yeong-Bae
    • 한국기계연구소 소보
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    • pp.37-46
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    • 1985
  • Properties of Precursor pitch derived from petroleum residue were studied physical and chemical analysis method for investigation of production of pitch fiber. For preparing of those precursor pitches it was carried out a temperature and time variation experiment i reactor. It was demonstrated the precursor pitch prepared in this study to have a similar properties to Ashland precursor pitch capable of bulk mesophase formation from the results of the basic analysis, that is, molecular weight distribution, coking yield, carbon content, chemical composition, etc.

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Improvement of MOD Processing by Applying F-free Y & Cu Precursor Solution (F-free Y & Cu 전구용액 적용에 의한 YBCO coated conductors의 MOD 공정 개선)

  • Kim, Y.K.;Yoo, J.M.;Chung, K.C.;Ko, J.W.;Cho, Y.S.;Heo, E.O.
    • Progress in Superconductivity
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    • v.8 no.1
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    • pp.22-26
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    • 2006
  • Total Fluorine content in the precursor solution for MOD processing of YBCO coated conductors can be significantly reduced by synthesizing precursor solution with F-free Y & Cu precursor and Barium trifluoroacetate(TFA). It was shown that crack-free and uniform precursor films were formed after calcinations in humidified oxygen atmosphere. Less than 2 hours are required to finish the calcination process, and XRD measurement shows that $BaF_2,\;CuO,\;and\;Y_2O_3$ are major constituent of calcined precursor films. Film thickness after calcination was measured to be ${\sim}2.8$ um by applying slot-die coating method. In particular, addition of Samarium shows critical current of Ic=226 A/cm-w($Jc=3.4\;MA/cm^2$). Also discussed are recent developments in the reel-to-reel processing using F-free Y & Cu precursor solutions. It is shown that uniform and fast processing route to YBCO coated conductor with high Ic can be provided by employing F-free Y & Cu precursor solutions in MOD process.

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Synthesis of F-free Y & Cu precursor solution and optimization of annealing process (Sm 첨가 F-free Y & Cu 전구용액의 합성 및 열처리 공정의 최적화)

  • Kim, Young-Kuk;Yoo, Jai-Moo;Chung, Kook-Chae;Ko, Jae-Woong
    • Progress in Superconductivity and Cryogenics
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    • v.9 no.1
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    • pp.1-4
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    • 2007
  • The total Fluorine content in the precursor solution for MOD processing of YBCO coated conductors can be significantly reduced by synthesizing precursor solution with F-free Y & Cu precursor and Barium trifluoroacetate(TFA). It was shown that crack-free and uniform precursor films were formed after calcinations in humidified oxygen atmosphere. Less than 2 hours are required to finish the calcinations process and XRD measurement shows that $BaF_2,\;CuO,\;Y_2O_3$ are major constituent of calcined precursor films. Film thickness after calcinations was improved to be 2.8um by applying slot-die coating method. In particular, addition of Samarium shows critical current of $I_c=273A/cm-w(J_c=3.8MA/cm^2)$. It is shown that uniform and fast processing route to YBCO coated conductor with high Ic can be provided by employing F-free Y & Cu precursor solution in MOD process.