• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1485-1486
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• 2011

A layer of $TiO_2$ thin film less than ~500nm in thickness, as a blocking layer, was coated by sol-gel method directly onto the anode electrode to be isolated from the electrolyte in dye-sensitized solar cells (DSCs). This is to prevent the electrons from back-transferring from the electrode to the electrolyte (I-/I3-). The effects of heat treatment conditions of the gel and as-coated film on the thickness and consolidation to substrate were studied. The flexible DSCs were fabricated with working electrode of Ti thin foil coated with blocking $TiO_2$ layer, dye-attached mesoporous $TiO_2$ film, gel electrolyte and counter electrode of Pt-deposited indium doped tin oxide/polyethylene naphthalate (ITO/PEN). The photo-current conversion efficiency of the cell was 5.3% ($V_{oc}=0.678V$, $J_{sc}=12.181mA/cm^2$, ff=0.634) under AM1.5, 100 mW/$cm^2$ illumination.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.258.2-258.2
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• 2015

염료감응형 태양전지(Dye-Sensitized Solar Cells; DSSC)는 공정비용과 재료가 저렴하여 차세대 태양전지로 각광받고 있다. 특히 투명한 재료를 사용하므로 flexible한 기판을 이용하여 그 적용범위가 넓다. DSSC는 상부전극인 FTO와 전해질의 접촉으로 인해 일부 FTO의 전자가 외부로 나가지 못하고 산화환원 반응에 의해 도로 전해질로 들어갈 확률이 있다. 이로 인해 효율 감소문제를 야기 할 수 있다. 이를 해결하기 위해 FTO위에 여러 물질들을 증착하거나 코팅 등의 많은 연구가 이루어져 왔다. ZnO를 DSSC로 적용한 연구는 많이 이루어졌지만 대부분 공정이 Chemical Vapor Deposition (CVD)으로 진행 되어왔다. 본 연구에서는 FTO위에 ZnO를 진공 공정에 비해 저렴하고 간단한 spin-coating으로 blocking layer를 형성하였다. 그 후 염료에서 여기 된 전자를 FTO로 전달해 주는 역할을 하는 TiO2를 doctor blade방법으로 형성하였다. ZnO는 TiO2하고 전도대와 가전자대의 에너지 준위 차이가 거의 없고, ZnO의 전자 이동도가 TiO2보다 높기 때문에 FTO로 전자를 큰 저항 없이 전달 할 수 있다. 또한 투과율이 좋아 염료까지의 빛의 투과성도 뛰어나다. ZnO blocking layer를 형성하여 FTO에서 전해질로의 전자이동을 막아주는 역할을 하여 DSSC의 performance 향상을 확인하였다. Field Emission Scanning Electron Microscope(FE-SEM)을 통해 FTO/ZnO/TiO2의 계면 및 두께를 확인하였고. DSSC의 특성 분석을 위해 I-V curve, Power conversion efficiency, Impedance spectroscopy를 측정 하였다.

• Korean Journal of Metals and Materials
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• v.48 no.5
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• pp.449-455
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• 2010

To enhance the efficiency of dye sensitized solar cells, we proposed crystalline anatase-$TiO_{2}$ by using a low temperature process ($150^{\circ}C{\sim}250^{\circ}C$). We successfully fabricated 30 nm-$TiO_{2}$ at a fixed atomic layer deposition condition of 1.0 sec of TDMAT pulse, 20 sec of TDMAT purge, 0.5 sec of H$_{2}$O pulse, and 20 sec of H$_{2}$O purge. In order to examine the microstructure, phase, and band-gap of the TiO$_{2}$ respectively, we employed a Nano-Spec, transmission electron microscope, high resolution XRD, Auger electron spectroscopy, scanning probe microscope, and UV-VIS-NIR. We were able to fabricate a crystalline anatase-phase of 30 nm-TiO$_{2}$ successfully at temperatures above $180^{\circ}C$. Our results showed that our proposed low temperature ALD process (below $200^{\circ}C$) might be applicable to glass and flexible polymer substrates.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.947-954
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• 2015

The homogeneous coating of a flexible film that is applied to dye-sensitized solar cells is related to the performance and durability of the product. The applied coating is obtained from the uniform temperature distribution and the mass flow rate in the nozzle of the hot air dryer. In this study, we determine the uniform temperature distribution and mass flow rate of each nozzle by performing numerical simulations to understand how various factors affect the performance of the hot air dryer. The numerical model is composed of the momentum equation for flow motion and the energy equation for temperature. In addition, we compare the numerical results to the experimental results to validate the model. Based on the results, the round-hole plate inside the hot air dryer significantly affects the uniform temperature and the mass flow rate.