• Title, Summary, Keyword: Nanophotonics

Search Result 33, Processing Time 0.038 seconds

Surfactant-treated graphene oxide in organic solvents and its application in photovoltaic cells

  • Wang, Yishan;Yang, Shengyi;Wang, Haowei;Zhang, Li;Cheng, Haijuan;He, Bo;Li, Weile;Zou, Bingsuo
    • Current Applied Physics
    • /
    • v.17 no.3
    • /
    • pp.343-350
    • /
    • 2017
  • In this paper, a simple and non-poisonous "surfactant treatment" method to prepare graphene oxide (GO) in organic solvents with good dispersibility was presented. As the surfactant molecules, didodecyldimethyla-mmonium bromide (DDAB) was attached onto the GO sheets via ionic interactions by mild sonication, the obtained GO:DDAB nanocomposites were then blended into copolymer Poly(3-hexylthiophene-2,5-diyl) (P3HT) [6,6]:-Phenyl $C_{61}$ butyric acid methyl ester ($PC_{61}BM$) as the active layer to fabricate bulk-heterojunction (BHJ) organic solar cells ITO/PEDOT:PSS/P3HT:$PC_{61}BM$:(GO:DDAB)/Ca/Al. The concentration of GO:DDAB in the active layer, a maximum power conversion efficiency (PCE) of 3.67% was obtained by blending 0.5 mg/mL GO:DDAB in the active layer, showing an efficiency increment of 13.35% as compared with that of the control device without doping GO:DDAB. The optimized OPVs with $PTB7:PC_{71}BM$ by adding GO:DDAB shows the PCE of 7.96%. Therefore, it paves a way to get high efficiency organic photovoltaic cells by directly blending surfactant-treated graphene oxide in organic solvent.

Effect of Thermal Treatment on the Performance and Nanostructures in Polymer Solar Cells with PTB7-Th:PC71BM Bulk Heterojunction Layers

  • Lee, Sooyong;Seo, Jooyeok;Jeong, Jaehoon;Lee, Chulyeon;Song, Myeonghun;Kim, Hwajeong;Kim, Youngkyoo
    • Current Photovoltaic Research
    • /
    • v.5 no.3
    • /
    • pp.69-74
    • /
    • 2017
  • Here we report the influence of thermal treatment on the performance of high efficiency polymer solar cells with the bulk heterojunction films of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b'] dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxylate] (PTB7-Th) and [6,6]-phenyl $C_{71}$ butyric acid methyl ester ($PC_{71}BM$). The crystalline nanostructure of PTB7-Th:$PC_{71}BM$ layers, which were annealed at three different temperatures, was investigated by employing synchrotron radiation grazing incidence X-ray diffraction (GIXD) technique. Results showed that the device performance was slightly reduced by thermal annealing at $50^{\circ}C$ but became significantly poor by thermal annealing at $100^{\circ}C$. The poor device performance by thermal annealing was attributed to the collapse in the crystalline nanostructure of PTB7-Th in the PTB7-Th:$PC_{71}BM$ layers as evidenced by the GIXD measurements that exhibited huge reduction in the intensity of PTB7-Th (100) peak even at $50^{\circ}C$.

Active microneedle actuated by thermopneumatic force (열 공압을 이용한 능동 미세바늘의 제작)

  • An J.Y.;Hwang I.H.;You S.K.;Lee J.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • /
    • pp.694-697
    • /
    • 2005
  • This paper presents a novel movable microneedle that becomes active when necessary to use. Conventional researches have been focused on the fabrication of microneedles and the interface with fluidic chip [1,2]. Therefore, we proposed an active microneedle to sample body fluids or deliver drugs in a controlled amount by actuating the needles. This allows us to keep the needles in operation only when necessary so that both the body skin and the needles can be protected from undesirable external disturbance while no operation.

  • PDF

Coherent Absorption Spectroscopy with Supercontinuum for Semiconductor Quantum Well Structure

  • Byeon, Ciare C.;Oh, Myoung-Kyu;Kang, Hoon-Soo;Ko, Do-Kyeong;Lee, Jong-Min;Kim, Jong-Su;Choi, Hyoung-Gyu;Jeong, Mun-Seok;Kee, Chul-Sik
    • Journal of the Optical Society of Korea
    • /
    • v.11 no.3
    • /
    • pp.138-141
    • /
    • 2007
  • We suggest that supercontinuum can be used for absorption spectroscopy to observe the exciton levels of a semiconductor nano-structure. Exciton absorption spectrum of a GaAs/AlGaAs quantum well was observed using supercontinuum generated by a microstructrured fiber pumped by a femtosecond (fs) pulsed laser. Significantly narrower peaks were observed in the absorption spectrum from 11 K up to room temperature than photoluminescence (PL) spectrum peaks. Because supercontinuum is coherent light and can readily provide high enough intensity, this method can provide a coherent ultra-broad band light source to identify exciton levels in semiconductors, and be applicable to coherent nonlinear spectroscopy such as electromagnetically induced transparency (EIT), lasing without inversion (LWI) and coherent photon control in semiconductor quantum structures.

Single-mode Condition and Dispersion of Terahertz Photonic Crystal Fiber

  • Kim, Soan;Kee, Chul-Sik;Lee, Jong-Min
    • Journal of the Optical Society of Korea
    • /
    • v.11 no.3
    • /
    • pp.97-100
    • /
    • 2007
  • We have investigated properties of a plastic photonic crystal fiber guiding terahertz radiations, THz photonic crystal fiber. The single-mode condition and dispersion of a plastic triangular THz photonic crystal fiber are investigated by using the plane wave expansion method and the beam propagation method. The THz photonic crystal fiber can perform as a single-mode fiber below 2.5 THz when the ratio of diameter (d) and period (${\Lambda}$) of air holes is less than 0.475. The THz photonic crystal fiber with ${\Lambda}=500{\mu}m$ and $d/{\Lambda}=0.4$ shows almost zero flattened dispersion behavior, $-0.03{\pm}0.02 ps/THz{\cdot}cm$, in the THz frequency range from 0.8 to 2.0 THz.

Investigation of short-term stability in high efficiency polymer : nonfullerene solar cells via quick current-voltage cycling method

  • Lee, Sooyong;Seo, Jooyeok;Kim, Hwajeong;Song, Dong-Ik;Kim, Youngkyoo
    • The Korean Journal of Chemical Engineering
    • /
    • v.35 no.12
    • /
    • pp.2496-2503
    • /
    • 2018
  • The short-term stability of high efficiency polymer : nonfullerene solar cells was investigated by employing a quick (ten cycles) current density-voltage (J-V) cycling method. Polymer : nonfullerene solar cells with initial power conversion efficiency (PCE) of >10% were fabricated using bulk heterojunction (BHJ) films of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5,7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6/7-methyl)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (IT-M). One set of the BHJ (PBDB-T : IT-M) films was thermally annealed at $160^{\circ}C$ for 30min, while another set was used without any thermal treatment after spin-coating. The quick J-V scan (cycling) measurement disclosed that the PCE decay was relatively slower for the annealed BHJ layers than the unannealed (as-cast) BHJ layers. As a result, after ten cycles, the annealed BHJ layers delivered higher PCE than the unannealed BHJ layers due to higher and more stable trend in fill factor. The present quick J-V cycling method is simple but expected to be useful for the prediction of short-term stability in organic solar cells.

A Brief Investigation on the Performance Variation and Shelf Lifetime in Polymer:Nonfullerene Solar Cells

  • Lee, Sooyong;Kim, Hwajeong;Lee, Chulyeon;Kim, Youngkyoo
    • Current Photovoltaic Research
    • /
    • v.7 no.3
    • /
    • pp.55-60
    • /
    • 2019
  • Polymer:nonfullerene solar cells with an inverted-type device structure were fabricated by employing the bulk heterojunction (BHJ) active layers, which are composed of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophene-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(6-methyl-2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3-d']-s-indaceno[1,2-b:5,6-b']dithiophene (IT-M). The BHJ layers were formed on a pre-patterned indium-tin oxide (ITO)-coated glass substrate by spin-coating using the blend solutions of PBDB-T and IT-M. The solar cell performances were investigated with respect to the cell position on the ITO-glass substrates. In addition, the short-term shelf lifetime of solar cells was tested by storing the PBDB-T:IT-M solar cells in a glovebox filled with inert gas. The results showed that the performance of solar cells was relatively higher for the cells close to the center of substrates, which was maintained even after storage for 24 h. In particular, the PCE of PBDB-T:IT-M solar cells was marginally decreased after storage for 24 h owing to the slightly reduced fill factor, even though the open circuit voltage was unchanged after 24 h.