Quantum Dot Sensitized Solar Cells Based on TiO2/AgInS2

Sachin A. Pawar,정재필,Dipali S. Patil,Vivek M. More,Rochelle S. Lee,신재철,최원준 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.10

Quantum dot heterojunctions with type-II band alignment can efficiently separate photogenerated electron-hole pairs and, hence, are useful for solar cell studies. In this study, a quantum dot sensitized solar cell (QDSSC) made of TiO2/AgInS2 is achieved to boost the photoconversion efficiency for the TiO2-based system by varying the AgInS2 layer’s thickness. The TiO2 nanorods array film is prepared by using a simple hydrothermal technique. The formation of a AgInS2 QD-sensitized TiO2-nanorod photoelectrode is carried out by successive ionic layer adsorption and reaction (SILAR) technique. The effect of the QD layer on the performance of the solar cell is studied by varying the SILAR cycles of the QD coating. The synthesized electrode materials are characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy and solar cell performances. The results indicate that the nanocrystals have effectively covered the outer surfaces of the TiO2 nanorods. The interfacial structure of quantum dots (QDs)/TiO2 is also investigated, and the growth interface is verified. A careful comparison between TiO2/AgInS2 sensitized cells reveals that the trasfer of electrons and hole proceeds efficiently, the recombination is suppressed for the optimum thickness of the QD layer and light from the entire visible spectrum is utilised. Under AM 1.5G illumination, a high photocurrent of 1.36 mAcm−2 with an improved power conversion efficiency of 0.48% is obtained. The solar cell properties of our photoanodes suggest that the TiO2 nanorod array films co-sensitized by AgInS2 nanoclusters have potential applications in solar cells.

Direct successive ionic layer adsorption and reaction (SILAR) synthesis of nickel and cobalt hydroxide composites for supercapacitor applications

Lee, Damin,Xia, Qi Xun,Mane, Rajaram S.,Yun, Je Moon,Kim, Kwang Ho ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.722 No.-

<P><B>Abstract</B></P> <P>Mesoporous nickel and cobalt hydroxide composites are directly grown onto 3D macro-porous Ni foam as a binder-free electrode for supercapacitors by using the successive ionic layer adsorption and reaction (SILAR) method. This method is the cheapest and simplest among several deposition processes for supercapacitor applications. An as-obtained porous NiCo(OH)<SUB>2</SUB> electrode exhibits a remarkable specific capacity (1113.6 mAh g<SUP>−1</SUP> at a current density of 3 A g<SUP>−1</SUP>) and excellent cycling stability (85.62% capacity retention after 5000 cycles). Furthermore, an asymmetric supercapacitor assembled with NiCo(OH)<SUB>2</SUB> as a positive electrode and graphene as a negative electrode shows a high energy density of 20.07 W h kg<SUP>−1</SUP> at a power density of 2302.73 W kg<SUP>−1</SUP> and excellent cycling stability (76.46% retention after 5000 cycles). As a result, it shows that the NiCo(OH)<SUB>2</SUB> fabricated by the SILAR method can be a promising electrode towards energy-storage devices with high energy and power densities.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SILAR method is a process conducted under mild conditions for 30 s. </LI> <LI> NiCo(OH)<SUB>2</SUB> composite by SILAR method is a 3D flower-like porous nanostructure. </LI> <LI> The synthesized NiCo(OH)<SUB>2</SUB> electrode shows high electrochemical performances. </LI> <LI> The specific capacity of the NiCo(OH)<SUB>2</SUB> electrode is 1113.6 mAh g<SUP>−1</SUP> at 3 A g<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

스테인리스강 기판에 연속 이온 층 흡착 및 반응 (SILAR) 공정을 통한 CoS 코팅 및 슈퍼캐패시터 전극 특성

김재승(Jaeseung Kim),이재원(Jaewon Lee),Vijay Shamrao Kumbhar,최진섭(Jinsub Choi),이기영(Kiyoung Lee) 한국표면공학회 2019 한국표면공학회지 Vol.52 No.3

In this study, the cobalt sulfide (CoS) nanosheet on stainless steel as a supercapacitor electrode is synthesized by using a facile successive ionic layer adsorption reaction (SILAR) method. The number of cycles for dipping and rinsing can control the nanosheet thickness of CoS on stainless steel. Field emission-scanning electron microscopy (FE-SEM) showed a layer structure of CoS particles coupled as agglomeration. And x-ray diffraction (XRD) showed the crystallinity of the CoS nanosheet. To investigate the characteristics of the CoS nanosheet electrode as the supercapacitor, analysis of electrochemical measurement was conducted. Finally, the CoS nanosheet of 70cycles on stainless steel shows the specific capacitance (44.25 mF/cm² at 0.25 mA/cm²) with electrochemical stability of 78.5% over during 2000cycles.

Quantum dot sensitized solar cell based on TiO₂/CdS/Ag₂S heterostructure

Pawar, Sachin A.,Patil, Dipali S.,Kim, Jin Hyeok,Patil, Pramod S.,Shin, Jae Cheol Elsevier 2017 Optical Materials Vol.66 No.-

<P><B>Abstract</B></P> <P>Quantum dot sensitized solar cell (QDSSC) is fabricated based on a stepwise band structure of TiO<SUB>2</SUB>/CdS/Ag<SUB>2</SUB>S to improve the photoconversion efficiency of TiO<SUB>2</SUB>/CdS system by incorporating a low band gap Ag<SUB>2</SUB>S QDs. Vertically aligned TiO<SUB>2</SUB> nanorods assembly is prepared by a simple hydrothermal technique. The formation of CdS and Ag<SUB>2</SUB>S QDs over TiO<SUB>2</SUB> nanorods assembly as a photoanode is carried out by successive ionic layer adsorption and reaction (SILAR) technique. The synthesized electrode materials are characterized by XRD, XPS, field emission scanning electron microscopy (FE-SEM), Optical, solar cell and electrochemical performances. The results designate that the QDs of CdS and Ag<SUB>2</SUB>S have efficiently covered exterior surfaces of TiO<SUB>2</SUB> nanorods assembly. A cautious evaluation between TiO<SUB>2</SUB>/CdS and TiO<SUB>2</SUB>/CdS/Ag<SUB>2</SUB>S sensitized cells tells that CdS and Ag<SUB>2</SUB>S synergetically helps to enhance the light harvesting ability. Under AM 1.5G illumination, the photoanodes show an improved power conversion efficiency of 1.87%, in an aqueous polysulfide electrolyte with short-circuit photocurrent density of 7.03 mA cm<SUP>−2</SUP> which is four fold higher than that of a TiO<SUB>2</SUB>/CdS system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> QDSSC fabrication using 1D TiO<SUB>2</SUB> nanostructures. </LI> <LI> High surface area for QDs loading. </LI> <LI> Strong absorption in the visible regime for TiO<SUB>2</SUB>/CdS/Ag<SUB>2</SUB>S. </LI> <LI> The QDSSC show improved photocurrents. </LI> <LI> High power conversion efficiency of 1.87%. </LI> </UL> </P>

TiO₂/CdS 복합광촉매의 밴드갭 에너지 특성과 광촉매 효율

이종호,허수정,윤정일,김영직,서수정,오한준,Lee, Jong-Ho,Heo, Sujeong,Youn, Jeong-Il,Kim, Young-Jig,Suh, Su-Jeong,Oh, Han-Jun 한국재료학회 2019 한국재료학회지 Vol.29 No.12

To improve photocatalytic performance, CdS nanoparticle deposited TiO₂ nanotubular photocatalysts are synthesized. The TiO₂ nanotube is fabricated by electrochemical anodization at a constant voltage of 60 V, and annealed at 500 for crystallization. The CdS nanoparticles on TiO₂ nanotubes are synthesized by successive ionic layer adsorption and reaction method. The surface characteristics and photocurrent responses of TNT/CdS photocatalysts are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis spectrometer and LED light source installed potentiostat. The bandgaps of the CdS deposited TiO₂ photocatalysts are gradually narrowed with increasing of amounts of deposited CdS nanoparticles, which enhances visible light absorption ability of composite photocatalysts. Enhanced photoelectrochemical performance is observed in the nanocomposite TiO₂ photocatalyst. However, the maximum photocurrent response and dye degradation efficiency are observed for TNT/CdS30 photocatalyst. The excellent photocatalytic performance of TNT/CdS30 catalyst can be ascribed to the synergistic effects of its better absorption ability of visible light region and efficient charge transport process.

Bimetallic Sulfide Thin Film Electrode for Efficient Water Oxidation

Shital Kale,Jin Hyeok Kim(김진혁) 한국신재생에너지학회 2020 한국신재생에너지학회 학술대회논문집 Vol.2020 No.8