• Title/Summary/Keyword: Kelvin Probe Force Microscopy (KPFM)

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Nano-size Study of Surface-modified Ag Anode for OLEDs (표면처리에 의한 유기발광소자(OLED)용 Ag 전극의 Nano-size 효과 연구)

  • Kim, Joo-Young;Kim, Soo-In;Lee, Kyu-Young;Kim, Hyeong-Keun;Jun, Jae-Hyeok;Jeong, Yun-Jong;Kim, Mu-Chan;Lee, Jong-Rim;Lee, Chang-Woo
    • Journal of the Korean Vacuum Society
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    • v.21 no.1
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    • pp.12-16
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    • 2012
  • Although silver is used for T-OLED (Top emitting organic Light-Emitting Diode) as reflective anode, it is not an ideal material due to its low work function. Thus, we study the effect of annealing and atmospheric pressure plasma treatment on Ag film that increases its work function by forming the thin silver oxide layer on its surface. In this study, we deposited silver on glass substrate using RF sputtering. Then we treated the Ag samples annealing at $300^{\circ}C$ for 30 minutes in atmosphere or treating the atmospheric plasma treatment for 30, 60, 90, 120s, respectively. We measured the change of the mechanical properties and the potential value of surface with each one at a different treatment type and time. We used nano-indenter system and KPFM (Kelvin Probe Force Microscopy). KPFM method can be measured the change of surface potential. The nanoindenter results showed that the plasma treatment samples for 30s, 120s had very low elastic modulus, hardness and Weibull modulus. However, annealed sample and plasma treated samples for 60s and 90s had better mechanical properties. Therefore, plasma treatment increases the uniformity thin film and the surface potential that is very effective for the performace of T-OLED.

Local surface potential and current-voltage behaviors of $Cu(In,Ga)Se_2$ thin-films with different Ga/(In+Ga) content (Ga/(In+Ga) 함량비에 따른 $Cu(In,Ga)Se_2$ 박막의 국소적 영역에서의 표면 퍼텐셜과 전류-전압 특성 연구)

  • Kim, G.Y.;Jeong, A.R.;Jo, W.;Jo, H.J.;Kim, D.H.;Sung, S.J.;Hwang, D.K.;Kang, J.K.;Lee, D.H.
    • 한국태양에너지학회:학술대회논문집
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    • 2012.03a
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    • pp.149-152
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    • 2012
  • $Cu(In,Ga)Se_2$ (CIGS) is one of the most promising photovoltaic materials because of large conversion efficiency which has been achieved with an optimum Ga/(In+Ga) composition in $CuIn_{1-x}Ga_xSe_2$ (X~0.3). The Ga/(In+Ga) content is important to determine band gap, solar cell performances and carrier behaviors at grain boundary (GB). Effects of Ga/(In+Ga) content on physical properties of the CIGS layers have been extensively studied. In previous research, it is reported that GB is not recombination center of CIGS thin-film solar cells. However, GB recombination and electron-hole pair behavior studies are still lacking, especially influence of with different X on CIGS thin-films. We obtained the GB surface potential, local current and I-V characteristic of different X (00.7 while X~0.3 showed higher potential than 100 mV on GBs. Higher potential on GBs appears positive band bending. It can decrease recombination loss because of carrier separation. Therefore, we suggest recombination and electron-hole behaviors at GBs depending on composition of X.

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