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Bogyu Kim,Younguk Jeon,Hyebi Kim,Chulwoo Lee,JoonHyun Kang,Jongbum Kim,In Soo Kim,Young-Hwan Kim,Kwanil Lee,Young Duck Kim,Il Ki Han 한국진공학회 2021 한국진공학회 학술발표회초록집 Vol.2021 No.2
Potassium tantalate niobate (KTal-xNbxO3, KTN) is a ferroelectric material with an extremely high electro-optic (EO) coefficient suitable for integrated photonic device. In the K-Ta-Nb-O system, the perovskite structure KTN with the ferroelectric properties is generally hard to deposit due to high volatility of potassium(K). By controlling K contents in a KTN ceramic target, the crystal structure can be formed from pyrochlore to perovskite phase. In this presentation, we will analyze the effects of K-enriched targets on the phase-formation process in KTN films and its structural differences.
Dielectric Function and Critical Points of SnS0.52Se0.48 in the Temperature Range from 27 to 350 K
Kim Tae Jung,Nguyen Xuan Au,Kim Bogyu,Kim Kyujin,Lee Wonjun,Kim Young Dong,르반롱,Nguyen Hoang Tung 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.11
We report the dielectric function ε = ε1+iε2 and the critical point (CP) energies of the orthorhombic SnS0.52Se0.48 alloy for the zigzag (a) and the armchair (b) directions in the spectral energy range from 0.74 to 6.42 eV and the temperature range from 27 to 350 K using spectroscopic ellipsometry. The CP energies were determined from the 2nd derivative spectra by using the standard analytic method. We observed sharpenings and blue-shifts of the CPs with decreasing temperature. We found thirteen and twelve CPs for the a- and the b-directions, respectively, at the lowest temperature while only eight and nine CPs were detected at room temperature. Also, an exciton effect was observed only in the armchair direction at low temperatures. The temperature dependences of the CP energies were determined by fitting the data to a phenomenological expression that contain the Bose-Einstein statistical factor and the temperature coefficient to describe the electron-phonon interaction.
Kim, Taehyo,Heo, Jungwoo,Lee, Ji Young,Yoon, Yung Jin,Lee, Tack Ho,Shin, Yun Seop,Kim, In-Sik,Kim, Hyojung,Jeong, Mun Seok,Hwang, In-Wook,Walker, Bright,Jo, Pil Sung,Lim, Bogyu,Kim, Jin Young American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.7
<P>In the field of organic solar cells, it has been generally accepted until recently that a difference in band energies of at least 0.3 eV between the highest occupied molecular orbital (HOMO) level of the donor and the HOMO of the acceptor is required to provide adequate driving force for efficient photoinduced hole transfer due to the large binding energy of excitons in organic materials. In this work, we investigate polymeric donor:non-fullerene acceptor junctions in binary and ternary blend polymer solar cells, which exhibit efficient photoinduced hole transfer despite negligible HOMO offset and demonstrate that hole transfer in this system is dependent on morphology. The morphology of the organic blend was gradually tuned by controlling the amount of ITIC and PC<SUB>70</SUB>BM. High external quantum efficiency was achieved at long wavelengths, despite ITIC-to-PC<SUB>70</SUB>BM ratio of 1:9, which indicates efficient photoinduced hole transfer from ITIC to the donor despite an undesirable HOMO energy offset. Transient absorption spectra further confirm that hole transfer from ITIC to the donor becomes more efficient upon optimizing the morphology of the ternary blend compared to that of donor:ITIC binary blend.</P> [FIG OMISSION]</BR>
Kim, Juhwan,Lim, Bogyu,Baeg, Kang-Jun,Noh, Yong-Young,Khim, Dongyoon,Jeong, Hyung-Gu,Yun, Jin-Mun,Kim, Dong-Yu American Chemical Society 2011 Chemistry of materials Vol.23 No.21
<P>We report synthesis and characterization of high performance p-type conjugated polymers containing alkyl-substituted thienylenevinylene (PC6TV12T and PC12TV12T) as an active layer for organic thin film transistors (OTFTs). Maximum mobility of annealed PC6TV12T and PC12TV12T films measured in OTFTs showed 0.47 and 1.05 cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP>, respectively, in the top-gate/bottom-contact (TG/BC) configuration.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2011/cmatex.2011.23.issue-21/cm2021802/production/images/medium/cm-2011-021802_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm2021802'>ACS Electronic Supporting Info</A></P>
Parameterization of the Dielectric Function of GaAsSb Alloy Films
Kim Tae Jung,Le Van Long,Nguyen Hoang Tung,Nguyen Xuan Au,Kim Bogyu,Kim Young Dong 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.10
The GaAsxSb1-x alloys are particularly promising materials for near-infrared light-emitting diode and detector devices. The optical properties, such as the dielectric function, complex refractive index, and absorption coefficient, are needed to properly design and understand semiconductor devices. Here, we report a method to obtain the optical properties of GaAsxSb1-x for the energy range from 1.5 to 6 eV and for an As composition from 0 to 1 at arbitrary wavelengths and compositions. The parameterization of the dielectric function of GaAsxSb1-x for specific compositions at x = 0, 0.183, 0.397, 0.528, 0.8, and 1 were realized by using the dielectric function parametric model.
Synergistic Effects of Terpolymer Regioregularity on the Performance of All-Polymer Solar Cells
Kim, Sang Woo,Kim, Honggi,Lee, Jin-Woo,Lee, Changyeon,Lim, Bogyu,Lee, Jaechol,Lee, Youngu,Kim, Bumjoon J. American Chemical Society 2019 Macromolecules Vol.52 No.2
<P>Random terpolymers with three different monomer units can provide broader light absorption than the most widely used donor-acceptor (D-A) alternating copolymers, but their electrical properties are often sacrificed by the randomly distributed monomers in the polymeric backbone that prevent efficient intermolecular π-π interactions. Here, we report the development of a regioregular terpolymer and demonstrate its importance in enhancing the power conversion efficiency (PCE) of all-polymer solar cells (all-PSCs). To investigate the impact of the monomer sequence and regioregularity in the terpolymer, we designed and synthesized two terpolymers (Ra-(D<SUB>1</SUB>-A-D<SUB>2</SUB>-A) random terpolymer and RR-(D<SUB>1</SUB>-A-D<SUB>2</SUB>-A) regioregular terpolymer) consisting of two electron-donating benzodithiophene (BDT) units with different side chains and one electron-withdrawing fluorinated thieno[3,4-<I>b</I>]thiophene (TT-F) unit. As a reference polymer, we also synthesized the D<SUB>1</SUB>-A alternating copolymer. The RR-(D<SUB>1</SUB>-A-D<SUB>2</SUB>-A) film exhibited stronger π-π stacking and a larger crystallite size than the D<SUB>1</SUB>-A and Ra-(D<SUB>1</SUB>-A-D<SUB>2</SUB>-A) films, resulting in 1 order of magnitude higher hole mobility than those of the other polymers. When blended with the P(NDI2HD-DTAN) polymer acceptor, the RR-(D<SUB>1</SUB>-A-D<SUB>2</SUB>-A)-based all-PSC yielded an outstanding PCE of 6.13%, which was superior to those of the D<SUB>1</SUB>-A-based all-PSCs (4.81%) and Ra-(D<SUB>1</SUB>-A-D<SUB>2</SUB>-A)-based all-PSCs (4.93%). These findings indicate that the synthesis of the regioregular terpolymer is a promising design strategy for the development of high-performance all-PSCs with improved optical and electrical properties.</P> [FIG OMISSION]</BR>
Kim, Taehyo,Lee, Ji Young,Heo, Jungwoo,Lim, Bogyu,Kim, Jin Young The Royal Society of Chemistry 2018 Polymer chemistry Vol.9 No.10
<P>We synthesized and characterized a new low band-gap copolymer, PBTTFB, incorporating <I>N</I>-alkylthieno[3,4-<I>c</I>]pyrrole-4,6-dione (TPD) as the acceptor and benzodithiophene (BDT) and (2,5-difluorophenylene)dithiophene as the donor units with S⋯F and S⋯O non-covalent intramolecular interactions. The PBTTFB polymer replaced bis(dodecyloxy)benzo[<I>c</I>][1,2,5]thiadiazole (BT) in P1, a previously reported polymer, with 5-dodecyl-4<I>H</I>-thieno[3,4-<I>c</I>]pyrrole-4,6(5<I>H</I>)-dione and exhibited improved macromolecular planarity and molecular ordering of the molecular structure. UV-vis absorption, electrochemical properties, bulk-heterojuction (BHJ) film morphology, and molecular ordering as well as photovoltaic charaterization derived from PBTTFB were studied and analyzed to explore the effect of the thienopyrroledione unit instead of the benzodithiophene unit in the molecular backbone of the polymer. From photovoltaic charaterization, we obtained an enhanced <I>J</I>sc value of 14.51 mA cm<SUP>−2</SUP> from the PBTTFB polymer compared to the <I>J</I>sc value of 10.54 mA cm<SUP>−2</SUP> from P1 due to improved macromolecular planarity. Furthermore, PBTTFB exhibited the highest PCE of 8.25% by adding DPE as a processing additive due to better interpenetration networks for improving charge transport and collection.</P>
A morphology controller for high-efficiency bulk-heterojunction polymer solar cells
Lim, Bogyu,Jo, Jang,Na, Seok-In,Kim, Juhwan,Kim, Seok-Soon,Kim, Dong-Yu The Royal Society of Chemistry 2010 Journal of materials chemistry Vol.20 No.48
<p>Controlling the morphology in bulk-heterojunction solar cells is the preferred and most effective way to achieve high efficiency. To control the morphology, we synthesized a novel hydrophobic end-functionalized <B>P3HT</B> to induce hydrophilic–hydrophobic repulsive interactions in the boundary between the relatively hydrophilic <B>PCBM</B> and the relatively hydrophobic <B>P3HT</B>. The introduction of hydrophobic end-functionalized <B>P3HT</B> (<B>F-P3HT</B>) leads to larger <B>PCBM</B> clusters, while maintaining the crystallinity of <B>P3HT</B> due to repulsive interactions. <B>F-P3HT</B> thus provides a maximized continuous interfacial area between the donor and the acceptor as well as bi-continuous networks of donor and acceptor domains, resulting in better percolation pathways for charge transport.</p> <P>Graphic Abstract</P><P>To control the morphology, we synthesized a hydrophobic end-functionalized <B>P3HT</B> (<B>F-P3HT</B>) to induce hydrophilic–hydrophobic repulsions interactions in the boundary between the relatively hydrophilic <B>PCBM</B> and the relatively hydrophobic <B>P3HT</B>. <B>F-P3HT</B> thus provides a maximized continuous interfacial area between the donor and the acceptor as well as bi-continuous networks of donor and acceptor domains, resulting in better percolation pathways for charge transport. <img src='http://pubs.rsc.org/ej/JM/2010/c0jm02296a/c0jm02296a-ga.gif'> </P>
Lim, Bogyu,Baeg, Kang‐,Jun,Jeong, Hyung‐,Gu,Jo, Jang,Kim, Hyungsoo,Park, Jeong‐,Woo,Noh, Yong‐,Young,Vak, Doojin,Park, Jeong‐,Ho,Park, Ji‐,Woong,Kim, Dong‐,Yu WILEY‐VCH Verlag 2009 Advanced Materials Vol.21 No.27
<P><B>A novel thiophene‐thienylenevinylene copolymer</B> is synthesized and evaluated for use in organic field‐effect transistors and organic solar cells. PETV12T shows good solution processability and high structural organization after annealing. Organic thin‐film transistors based on the polymer exhibit high mobility and a high resistance to oxidation. In addition, PETV12T shows potential as an electron donor in bulk heterojunction solar cells. </P>