김창순 교수

A simple and general postdeposition electrode patterning technique for active organic electronic devices is demonstrated and is applied to patterning the metal cathodes of organic light-emitting devices. Selective lift-off of the metal cathode layer is achieved by pressing a prepatterned, metal-coated silicon stamp on the unpatterned device layers. Under pressure, the metal coating on the stamp cold-welds to the metal cathode coating the underlying organic films. Subsequent separation of the sta

We demonstrate a patterning method capable of producing features of submicron scale based on the transfer of a metal film from a stamp to a substrate assisted by cold welding. The patterned metal film can be used as an etch mask to replicate the pattern on the substrate, or the film itself can serve as contact electrodes for a wide range of electronic devices. We demonstrate the versatility of the technique by fabricating a polymer grating on SiO2 with lateral dimensions <80 nm and a patt

Polymer electroluminescence devices producing circularly polarized luminescence (CP PLEDs) have valuable photonic applications. The fabrication of a CP PLED requires a polymer host that provides the appropriate chiral environment around the emitting dopant. However, chemical strategies for the design of chiral polymer hosts remain underdeveloped. We have developed new polymer hosts for CP PLED applications. These polymers were prepared through a free-radical polymerization of 3-vinylcarbazole wi

Circularly polarized luminescence (CPL) enables promising applications in asymmetric photonics. However, the performances of CPL molecules do not yet meet the requirements of these applications. The shortcoming originates from the trade-off in CPL between the photoluminescence quantum yield (PLQY) and the photoluminescence dissymmetry factor (gPL). In this study, we developed a molecular strategy to circumvent this trade-off. Our approach takes advantage of the strong propensity of [Pt(N^C^N)Cl]

We demonstrate the localized patterning of organic thin films based on direct material transfer from a stamp to a substrate. This process, based on van der Waals bonding between contacting organic films, extends the range of application of patterning via stamping to devices where the active organic materials must be locally deposited on the substrate. A mechanical analysis combined with finite element numerical simulations successfully describes the details of the material transfer process over

ABSTRACT In this article, we developed a dual‐band band‐pass filter (DB‐BPF) based on stepped impedance resonators (SIRs) using coupled feeding lines input and output ports. The developed filter allows the adjustment of the frequency and the bandwidth of the upper band (3.8 GHz) and the lower band (2.4 GHz). The transmission coefficients of the DB‐BPF are improved by maximizing the coupling between the SIRs. Furthermore, the capability of the rejection band is increased and the insertion losses

To build a large-scale quantum information processor (QIP) based on trapped ions or neutral atoms, integrated optical systems capable of delivering laser beams to multiple target locations are necessary. We consider a beam-shifting element consisting of a tilting micromirror located at the focal point of a lens, as a fundamental building block for such a system. We explore the design space of the micromirrors and characterize their dc, frequency, and transient responses. The fastest mirror featu

It is demonstrated that a stamp composed of a poly(dimethylsiloxane) (PDMS) bulk and perfluoropolyether (PFPE) coating fabricated by a simple dip-coating method has the following properties that are ideal for the transfer patterning of various materials. Deposited by a condensation reaction between PDMS and PFPE molecules as well as the adjacent PFPE molecules, the PFPE coating has a strong adhesion to the PDMS surface and strong internal cohesion, while providing a low energy surface. Furthermo

We propose a lateral-tandem organic photovoltaic system consisting of a dispersive-focusing element and continuously-tuned, series-connected sub-cells. The proposed system overcomes the efficiency limitation of organic photovoltaic devices by spectral re-distribution of incoming solar photons and their delivery to the wavelength-matched, resonant sub-cells. By numerical simulations, we demonstrate that optical resonance in a microcavity sub-cell with a metal/organic multilayer/metal structure ca

Interconnection layers (ICLs) for polymer tandem solar cells reported so far are limited in materials' choice and layer structure, because of a requirement that the ICLs must prevent the penetration of solvents used for the top cells. In this research, it is demonstrated that depositing the active layer of the top subcell using a dry thin-film transfer technique allows for incorporation of an ICL composed of vacuum deposited materials in a polymer tandem cell, providing a large degree of freedom