Publications by authors named "Jun-Seok Yeo"

Medium chain length Polyhydroxyalkanoate (mcl-PHA) is a biodegradable bioplastic material with promising applications in various fields, including the medical, packaging, and agricultural industries. This mcl-PHA can be biosynthesized by microorganisms from various carbon sources, and notably, it can also be produced from alkane mixtures contained in pyrolysis oil derived from low-grade waste plastics. In this study, Pseudomonas resinovorans was engineered to overexpress alkane monooxygenase from Lysinibaillus fusiformis JJY0216, enhancing its ability to utilize alkanes as carbon sources and thereby increasing mcl-PHA production.

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Solution-processable graphenes (represented by reduced graphene oxides, rGOs) have shown promising abilities as HTLs in perovskite solar cells (PeSCs). However, there has been no attempt to systematically tailor the characteristics of rGOs to the specifications of PeSCs. Furthermore, the applications of rGO HTLs have been limited to the spin-coating system, which is incompatible with roll-to-roll manufacturing.

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The type VI secretion system (T6SS) inhibits the growth of neighboring bacterial cells through a contact-mediated mechanism. Here, we describe a detailed characterization of the protein localization dynamics in the T6SS. It has been proposed that the type VI secretion process is driven by a conformational-change-induced contraction of the T6SS sheath.

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For the first time, the photovoltaic modules composed of small molecule were successfully fabricated by using roll-to-roll compatible printing techniques. In this study, blend films of small molecules, BTR and PCBM were slot-die coated using a halogen-free solvent system. As a result, high efficiencies of 7.

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We demonstrate that a bi-interlayer consisting of water-free poly(3,4-ethylenedioxythiophene) (PEDOT) and fluorinated reduced graphene oxide (FrGO) noticeably enhances the efficiency and the stability of the normal-structure perovskite solar cells (PeSCs). With simple and low temperature solution-processing, the PeSC employing the PEDOT + FrGO interlayer exhibits a significantly improved power conversion efficiency (PCE) of 14.9%.

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Despite the potential of roll-to-roll processing for the fabrication of perovskite films, the realization of highly efficient and reproducible perovskite solar cells (PeSCs) through continuous coating techniques and low-temperature processing is still challenging. Here, we demonstrate that efficient and reliable CHNHPbI (MAPbI) films fabricated by a printing process can be achieved through synergetic effects of binary processing additives, N-cyclohexyl-2-pyrrolidone (CHP) and dimethyl sulfoxide (DMSO). Notably, these perovskite films are deposited from premixed perovskite solutions for facile one-step processing under a room-temperature and ambient atmosphere.

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We report on the fabrication of an organic thin-film semiconductor formed using a blend solution of soluble ambipolar small molecules and an insulating polymer binder that exhibits vertical phase separation and uniform film formation. The semiconductor thin films are produced in a single step from a mixture containing a small molecular semiconductor, namely, quinoidal biselenophene (QBS), and a binder polymer, namely, poly(2-vinylnaphthalene) (PVN). Organic field-effect transistors (OFETs) based on QBS/PVN blend semiconductor are then assembled using top-gate/bottom-contact device configuration, which achieve almost four times higher mobility than the neat QBS semiconductor.

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We report the effect of binary additives on the fabrication of polymer solar cells (PSCs) based on a bulk heterojunction (BHJ) system. The combination of 1,8-diiodooctane (DIO), a high-boiling and selective solvent, for fullerene derivatives and poly(dimethylsiloxane) (PDMS) precursor, a nonvolatile insulating additive, affords complementary functions on the effective modulation of BHJ morphology. It was found that DIO and PDMS precursor each play different roles in the control of BHJ morphology, and thus, the power conversion efficiency (PCE) can be further enhanced to 7.

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The highly efficient CH3NH3PbI3 perovskite solar cell (PeSC) is simply achieved by employing a blended electron-transport layer (ETL) consisting of PC61BM and P(NDI2OD-T2). The high molecular weight of P(NDI2OD-T2) allows for a thinned ETL with a uniform morphology that optimizes the PC61BM ETL more effectively. As a result of this enhancement, the power conversion efficiency of a PC61BM:P(NDI2OD-T2)-based PeSC is 25% greater than that of the conventional PC61BM based-PeSC; additionally, the incorporation of P(NDI2OD-T2) into PC61BM attenuates the dependence of the PeSC on the ETL-processing conditions regarding its performance.

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Unlabelled: We demonstrate that an easily accessible polyacrylonitrile (PAN) polymer can efficiently function as a novel solution-processable anode interfacial layer (AIL) to boost the device performances of polymer:fullerene-based solar cells (PSCs). The PAN thin film was simply prepared with spin-coating of a cost-efficient PAN solution dissolved in dimethylformamide on indium tin oxide (ITO), and the thin polymeric interlayer on PSC parameters and stability were systemically investigated. As a result, the cell efficiency of the PSC with PAN was remarkably enhanced compared to the device using bare ITO.

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Perovskite solar cells (PeSCs) have been considered one of the competitive next generation power sources. To date, light-to-electric conversion efficiencies have rapidly increased to over 10%, and further improvements are expected. However, the poor device reproducibility of PeSCs ascribed to their inhomogeneously covered film morphology has hindered their practical application.

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The interfacial properties of PEDOT:PSS, pristine r-GO, and r-GO with sulfonic acid (SR-GO) in organic photovoltaic are investigated to elucidate electron-blocking property of PEDOT:PSS anode interfacial layer (AIL), and to explore the possibility of r-GO as electron-blocking layers. The SR-GO results in an optimized power conversion efficiency of 7.54% for PTB7-th:PC71BM and 5.

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Flexible organic solar cells (OSCs) composed of blended films of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were fabricated and investigated with chemically doped multilayer graphene films as transparent and conducting electrodes on plastic substrates. The sheet resistance of the chemically doped graphene film was reduced to half of its original value, resulting in a significant performance enhancement of OSCs featuring doped graphene electrodes. Moreover, there was no substantial variation observed in the fill factor and power conversion efficiency values of the flexible OSCs under bending conditions.

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In the present study, a novel polar-solvent vapor annealing (PSVA) was used to induce a significant structural rearrangement in poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films in order to improve their electrical conductivity and work function. The effects of polar-solvent vapor annealing on PEDOT:PSS were systematically compared with those of a conventional solvent additive method (SAM) and investigated in detail by analyzing the changes in conductivity, morphology, top and bottom surface composition, conformational PEDOT chains, and work function. The results confirmed that PSVA induces significant phase separation between excess PSS and PEDOT chains and a spontaneous formation of a highly enriched PSS layer on the top surface of the PEDOT:PSS polymer blend, which in turn leads to better 3-dimensional connections between the conducting PEDOT chains and higher work function.

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A novel donor-acceptor-type polymer with a low band-gap that alternates electron-rich thienylenevinylene groups with electron-deficient diketopyrrolopyrrole (DPP) units (PETVTDPP) has been synthesized by Pd-catalyzed Stille cross-coupling polymerization. The polymer shows a broad absorption band of wavelengths that range from 330 to 900 nm, and a low band-gap value of 1.43 eV.

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