Ki-Won Seo

Indium-free, highly transparent, flexible Cu2O/Cu/Cu2O mesh electrodes for flexible touch screen panels.

We report on an indium-free and cost-effective Cu2O/Cu/Cu2O multilayer mesh electrode grown by room temperature roll-to-roll sputtering as a viable alternative to ITO electrodes for the cost-effective production of large-area flexible touch screen panels (TSPs). By using a low resistivity metallic Cu interlayer and a patterned mesh structure, we obtained Cu2O/Cu/Cu2O multilayer mesh electrodes with a low sheet resistance of 15.1 Ohm/square and high optical transmittance of 89% as well as good mechanical flexibility. Outer/inner bending test results showed that the Cu2O/Cu/Cu2O mesh electrode had a mechanical flexibility superior to that of conventional ITO films. Using the diamond-patterned Cu2O/Cu/Cu2O multilayer mesh electrodes, we successfully demonstrated TSPS of the flexible film-film type and rigid glass-film-film type TSPs. The TSPs with Cu2O/Cu/Cu2O mesh electrode were used to perform zoom in/out functions and multi-touch writing, indicating that these electrodes are promising cost-efficient transparent electrodes to substitute for conventional ITO electrodes in large-area flexible TSPs.

Highly transparent and flexible InTiO/Ag nanowire/InTiO films for flexible organic solar cells

We investigated characteristics of Ti-doped In2O3 (TIO)/Ag nanowire (NW)/TIO films as potential transparent and flexible electrodes for flexible organic solar cells. Effective insertion of metallic Ag NW between TIO layers led to improvement of electrical and mechanical properties of sputtered TIO film. At optimized conditions, we achieved a flexible TIO/Ag NW/TIO multilayer with a low sheet resistance of 9.01 Ω/square and a high optical transmittance of 85.14%. In addition, the TIO/Ag NW/TIO multilayer electrode showed small inner and outer bending radius of 5 and 6.5 mm indicating good flexibility. This indicates that hybridization of sputtered TIO films and printed Ag NW network is a promising solution to solve critical problems of high resistance and brittle TIO film and Ag NW network with poor adhesion.

Simple brush painted Ag nanowire network on graphene sheets for flexible organic solar cells

The authors report on highly flexible and transparent Ag nanowire (NW) coated graphene hybrid electrodes for flexible organic solar cells (FOSCs). Brush painted Ag NW percolating network on the transparent graphene sheet led to an invisible Ag NW/graphene hybrid electrode with a sheet resistance of 15.25 Ω/sq. and a high optical transmittance of 77.4% as well as superior flexibility. In particular, similar bending radius of Ag NW/graphene hybrid electrode to graphene bilayer electrode during outer bending test demonstrated the superior mechanical flexibility of the Ag NW/graphene hybrid electrodes. FOSCs fabricated on Ag NW/graphene hybrid electrode showed higher power conversion efficiency (2.681%) than that (1.681%) of FOSC with graphene bilayer electrode due to lower sheet resistance and improved wettability for hole extracting layer. This indicates that brush painting of conductive Ag NW is a critical solution to solve the problem of high resistance and hydrophobic graphene electrode for use in FOSC.

Self-assembled Ag nanoparticle network passivated by a nano-sized ZnO layer for transparent and flexible film heaters

We investigated a self-assembled Ag nanoparticle network electrode passivated by a nano-sized ZnO layer for use in high-performance transparent and flexible film heaters (TFFHs). The low temperature atomic layer deposition of a nano-sized ZnO layer effectively filled the uncovered area of Ag network and improved the current spreading in the self-assembled Ag network without a change in the sheet resistance and optical transmittance as well as mechanical flexibility. The time-temperature profiles and heat distribution analysis demonstrate that the performance of the TFTH with the ZnO/Ag network is superior to that of a TFFH with Ag nanowire electrodes. In addition, the TFTHs with ZnO/Ag network exhibited better stability than the TFFH with a bare Ag network due to the effective current spreading through the nano-sized ZnO layer.

Ag-Pd-Cu alloy inserted transparent indium tin oxide electrodes for organic solar cells

The authors report on the characteristics of Ag-Pd-Cu (APC) alloy-inserted indium tin oxide (ITO) films sputtered on a glass substrate at room temperature for application as transparent anodes in organic solar cells (OSCs). The effect of the APC interlayer thickness on the electrical, optical, structural, and morphological properties of the ITO/APC/ITO multilayer were investigated and compared to those of ITO/Ag/ITO multilayer electrodes. At the optimized APC thickness of 8 nm, the ITO/APC/ITO multilayer exhibited a resistivity of 8.55 × 10−5 Ω cm, an optical transmittance of 82.63%, and a figure-of-merit value of 13.54 × 10−3 Ω−1, comparable to those of the ITO/Ag/ITO multilayer. Unlike the ITO/Ag/ITO multilayer, agglomeration of the metal interlayer was effectively relieved with APC interlayer due to existence of Pd and Cu elements in the thin region of the APC interlayer. The OSCs fabricated on the ITO/APC/ITO multilayer showed higher power conversion efficiency than that of OSCs prepared on the ITO/Ag...

Effect of Target–Substrate Distance on the Properties of Hetero Facing Target Sputtered Al–Ga–Zn–O Films

We investigated the effects of facing target–substrate distance (TSD) on the electrical, optical, structural and morphological properties of Al–Ga–Zn–O (AGZO) films grown by linear facing target sputtering (LFTS) at room temperature to optimize the TSD. Although the optimal TSD for depositing an AGZO film was 3 cm, based on figure of merit values, a longer TSD prevents plasma damage of the AGZO films. The AGZO film sputtered under optimized conditions had a sheet resistance of 132 Ohm/square and an optical transmittance of 87.2%. Based on the electrical, optical, structural, and surface properties of AGZO films grown at different TSDs, we suggest a possible mechanism to explain the effects TSD on properties of hetero-sputtered AGZO films prepared by LFTS process.