Kwang-Sup Lee

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We report polymeric nanomicelles doped with organic fluorophores (StCN, (Z)-2,3-bis[4-(N-4-(diphenylamino)styryl)phenyl]-acrylonitrile), which have the property of aggregation-enhanced fluorescence. The fluorescent nanomicelles have two unique features: (1) They give much brighter fluorescence emission than mono-fluorophores. (2) The nanomicelles with(More)
The precise mechanism and dynamics of charge generation and recombination in bulk heterojunction polymer:fullerene blend films typically used in organic photovoltaic devices have been intensively studied by many research groups, but nonetheless remain debated. In particular the role of interfacial charge-transfer (CT) states in the generation of free charge(More)
In this study, we report a neo-conceptive three-dimensionally (3D) crossing manifold micromixer (CMM) embedded in microchannel. Fabricated by sequential processes of photolithography and two photon absorption stereolithography, this leads to a microfluidic system with a built-in micromixer in a site controlled manner. The effectiveness of CMM is(More)
We have functionalized core-shell CdSe/ZnS quantum dots (QDs) with a photosensitive monolayer, rendering them solution processable and photopatternable. Upon exposure to ultraviolet radiation, films composed of this material were found to polymerize, forming interconnected arrays of QDs. The photoluminescence properties of the nanocrystal films increased(More)
A novel method for the fabrication of polypyrrole nanotubes (PPyNTs) possessing quantum dots (QDs) was developed for optoelectronic devices. PbSe QDs were effectively attached to the thiolated PPyNT-SH without affecting the dispersion stability of QDs and hence ensuring their homogeneous distribution in the polymer. Transmission electron microscopic images(More)
In this paper, the surface modification of CdSe- and CdZnS-based quantum dots (QDs) with a functional silica shell is reported. Functionalized silica shells are prepared by two routes: either by ligand exchange and a modified Stöber process or by a miniemulsion process with amphiphilic poly(oxyethylene) nonylphenylether also know as Igepal CO-520 (IG) as(More)
New hyperbranched polysiloxysilane (HBPS) materials containing terminal carboxylic acid and quaternary ammonium groups were designed and synthesized to obtain fluorescent-dye-encapsulated nanoparticles. These polymers exhibited desirable characteristics, including amphiphilicity for nanoparticle formation, and contained various terminal groups for(More)
A soluble truxene derivative (TR1) attached with triphenylamine at the peripheral position was designed and synthesized. The structure and purity of TR1 were carefully characterized by 1H NMR, UV/vis and photoluminescent spectroscopy, mass spectroscopy, and thermal analyses. It exhibited good solubility in common organic solvents and good film forming(More)
The exciton dynamics in pristine films of two structurally related low-bandgap diketopyrrolopyrrole (DPP)-based donor-acceptor copolymers and the photophysical processes in bulk heterojunction solar cells using DPP copolymer:PC71 BM blends are investigated by broadband transient absorption (TA) pump-probe experiments covering the vis-near-infrared spectral(More)
Quantum dots (QDs) are semiconductor nanocrystals with peculiar optoelectronic properties. Their wide application in light-emitting diodes, solar cells, and the medical and defense fields makes them a potential candidate in the area of photonics and biophotonics. In this feature issue of Optical Materials Express, together with Optics Express we focus on(More)