• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1471-1472
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• 2011

최근 경재적인 한계를 드러내고 있는 실리콘 태양전지의 대안으로 주목받고 있는 염료감응형 태양전지는 식물의 광합성 원리에 기초하여 빛이 입사하면 염료 분자가 포톤을 흡수해 여기하면서 전자를 방출함으로써 기전력을 발생시키는 원리로 동작한다. 염료에서 발생된 전자는 $TiO_2$의 conduction band로 주입되어 확산을 통해 TCO 기판으로 이동한다. 이때 다공성 나노구조의 $TiO_2$ 표면과 전해질의 접촉이 발생하게 되고 이로 인해 $TiO_2$ conduction band의 전자와 전해질의 $I_3{^-}$ 간의 재결합이 발생하게 되는데 이것은 DSC의 기능을 저하시키는 요인 중의 하나이다. 이러한 문제점은 $Al_2O_3$, ZnO, MgO, $BaTiO_2$ 등의 표면처리에 의한 core-shell 나노구조를 형성함으로써 해결할 수 있다. 본 연구에서는 aluminum isopropoxidee와 magnesium chloride 혼합 용액을 사용하여 core-shell 나노구조를 형성하여 셀을 제작하고, 완성된 셀의 출력특성과 내부 임피던스의 변화를 측정, 분석함으로써 단일 용액을 사용하였을 때에 비해 효과적인 재결합 감소와 광전압의 상승효과를 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.417-417
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• 2016

Global environmental deterioration has become more serious year by year and thus scientific interests in the renewable energy as environmental technology and replacement of fossil fuels have grown exponentially. Photoelectrochemical (PEC) cell consisting of semiconductor photoelectrodes that can harvest light and use this energy directly to split water, also known as photoelectrolysis or solar water splitting, is a promising renewable energy technology to produce hydrogen for uses in the future hydrogen economy. A major advantage of PEC systems is that they involve relatively simple processes steps as compared to many other H2 production systems. Until now, a number of materials including TiO2, WO3, Fe2O3, and BiVO4 were exploited as the photoelectrode. However, the PEC performance of these single absorber materials is limited due to their large charge recombinations in bulk, interface and surface, leading low charge separation/transport efficiencies. Recently, coupling of two materials, e.g., BiVO4/WO3, Fe2O3/WO3 and CuWO4/WO3, to form a type II heterojunction has been demonstrated to be a viable means to improve the PEC performance by enhancing the charge separation and transport efficiencies. In this study, we have prepared a triple-layer heterojunction BiVO4/WO3/SnO2 photoelectrode that shows a comparable PEC performance with previously reported best-performing nanostructured BiVO4/WO3 heterojunction photoelectrode via a facile solution method. Interestingly, we found that the incorporation of SnO2 nanoparticles layer in between WO3 and FTO largely promotes electron transport and thus minimizes interfacial recombination. The impact of the SnO2 interfacial layer was investigated in detail by TEM, hall measurement and electrochemical impedance spectroscopy (EIS) techniques. In addition, our planar-structured triple-layer photoelectrode shows a relatively high transmittance due to its low thickness (~300 nm), which benefits to couple with a solar cell to form a tandem PEC device. The overall PEC performance, especially the photocurrent onset potential (Vonset), were further improved by a reactive-ion etching (RIE) surface etching and electrocatalyst (CoOx) deposition.