정선호 교수

Ga doping in indium zinc oxide (IZO)-based amorphous-oxide semiconductors (AOSs) promotes the formation of oxide-lattice structures with oxygen vacancies at low annealing temperatures, which is essential for acceptable thin-film-transistor performance (see figure). The mobility dependence on annealing temperature and AOS composition are analyzed and the chemical role of Ga is clarified, as required for solution-processed, low-temperature-annealed AOSs. Detailed facts of importance to specialist

Abstract With the aim of preparing a high performance conductive ink, we sought to control the surface chemistry of Cu nanoparticles so as to minimize surface oxidation. Specifically, the surface oxide layer on Cu nanoparticles synthesized in ambient atmosphere was minimized by adjusting the molecular weight of poly( N ‐vinylpyrrolidone) capping molecules, as confirmed by high resolution transmission electron microscopy and X‐ray photoelectron spectroscopy analyses. In addition, we demonstrate t

High-performance, solution-processable semiconductors have drawn significant attention for use in low-cost, functional electronic applications. Metal oxide semiconductors are the most promising building blocks for high performance electronic devices because of their electrical properties and solution-processability. However, the major impediment for metal oxide semiconductors is that the electrical properties applicable to electronic devices are activated by chemical/physical structural evolutio

With the aim of inkjet printing highly conductive and well-defined Cu features on plastic substrates, aqueous based Cu ink is prepared for the first time using water-soluble Cu nanoparticles with a very thin surface oxide layer. Owing to the specific properties, high surface tension and low boiling point, of water, the aqueous based Cu ink endows a variety of advantages over conventional Cu inks based on organic solvents in printing narrow conductive patterns without irregular morphologies. It i

행동과학 연구자들은 흔히 회귀모형을 토대로 독립변수와 종속변수의 인과관계를 파악하고 더 나아가 이들의 관계를 제 3의 변수인 매개변수 또는 조절변수를 통해 질적으로 이해하는데 많은 노력을 기울여왔다. 최근에는 매개변수와 조절변수의 역할에 대한 통합적 이해를 위해 이들이 서로 결합된 형태로 제시된 매개된 조절효과와 조절된 매개효과를 연구하는데도 높은 관심을 보이고 있다. 하지만 여전히 많은 연구자들이 이 통합모형의 개념적 구분과 분석절차의 적용에 있어 적지 않은 혼란을 경험하고 있다. 본 논문에서 저자들은 연구모형과 통계모형 측면에서 매개된 조절효과와 조절된 매개효과의 공통점과 차이점을 논의하고 이를 회귀분석을 이용하여 검증하는 방법에 대해서 소개한다. 이 회귀분석 접근법은 이 통합모형을 탐색적으로 조사하기 위해 단계적 분석방법을 따르므로 이론개발을 목적으로 사용할 수 있는 연구방법이다. 본문에서 먼저 매개된 조절효과와 조절된 매개효과에 대한 개념적 구분과 방법론적 배경을 설명한다.

A zinc tin oxide (ZTO) semiconductor layer for thin-film transistor was fabricated using solution-processable sol−gel material. To obtain semiconductor characteristics, ZTO gels should be annealed such that salts and organic components in the ZTO layer undergo complete decomposition. The thermal behavior of ZTO precursor materials was investigated, and the electrical performances of solution-processed transistors were analyzed as a function of the annealing temperature of the ZTO semiconductor l

A high-performance piezoelectric nanocomposite generator (PNG) based on chemically reinforced composites is demonstrated by incorporating amine-functionalized lead zirconate titanate (PZT-NH₂) nanoparticles into a polymer matrix.

Air-stable, surface-oxide free Cu nanoparticles are, for the first time, synthesized by surrounding completely the Cu surface with oleic acid incorporated as a capping molecule. XPS analysis, in conjunction with TEM analysis, revealed that the oleic acid is chemisorbed to the Cu surface via a chemical interaction wherein a monodentate bond is included, without leaving behind free (non-interacting) oleic acid, thereby providing complete surface protection against oxidation. By eliminating the sur

Recent advances in unconventional foldable and stretchable electronics have forged a new field in electronics. However, traditional conducting metal oxides and metal thin films are inappropriate as electrodes for stretchable devices because they are vulnerable to tensile strain as well as bending strain. In this study, we describe the fabrication of annealing-free, copper nanowire (CuNW)-based stretchable electrodes using an inexpensive metal source through a simple and scalable process at low t

Although high dielectric constant (k) oxide thin film has been considered as a key element for high performance and low-voltage driven thin-film transistors (TFTs), there are no solution processable high-k oxide dielectrics that satisfy the stringent requirements of low-temperature processability, mechanical flexibility, and good TFT performance. Here, we demonstrate that the incorporation of a zirconium component that has strong bonding to oxygen enables a significant reduction in the processin

We demonstrate organic residue free, bandgap-graded Cu 2 Zn(Sn 1– x Ge x )S 4 (CZTGeS) thin-film solar cells based on metal chalcogenide complex (MCC) ligand capped nanocrystals (NCs). The bandgap of the CZTGeS films is tuned by varying the amount of Sn 2 S 6 4– MCC ligand absorbed on the surface of the Cu 2 ZnGeS 4 (CZGeS) NCs, without an undesirable postselenization process. Using CZGeS NCs inks with three different Sn/(Ge+Sn) ratios, bandgap-graded CZTGeS thin films are obtained via multicoat

Multiphase CuInSe2 (CISe) nanoparticles including the CuSe phase are synthesized by the microwave-assisted solvothermal method. Without additional processing, multiphase CISe nanoparticles facilitate the solution-processed CISe absorber layer with a dense microstructure, large grains, high crystallinity, and composition controllability, which are essential for acceptable thin-film solar cell performance. The high performance, solution-processed CISe solar cell, with a conversion efficiency of 8.

Sol–gel-derived oxide semiconductors annealed at a low temperature have been of great interest recently in various thin-film transistor (TFT) applications. However, studies on the influence of metal salt precursor on sol–gel-derived oxide semiconductor annealed at a low temperature have not yet been reported. In this study, the impact of metal salt precursor on the chemical structure evolution of Ga-doped In 2 O 3 (IGO) semiconductor and electrical performance of thin-film transistors with a cor

Recently, organometal halide perovskite (OMHP)‐based solar cells have been regarded as one of the most promising technologies in the research field of renewable energy applications. Along with successful demonstrations of high power conversion efficiencies (PCEs), various characteristic strategies for fabricating functional OMHP‐based solar cells have been exploited to facilitate both their practical applicability and industrial suitability. As a part of such efforts, unconventional transparent

We report the previously unrecognized co-solvent, formamide (FA), which can comprehensively improve both the device performance and bias stability of metal salt-derived, solution-processed In–Ga–Zn–O (IGZO) TFTs. By incorporating FA in IGZO precursor solutions, the chemical structures are tailored adequately for reducing the content of hydroxide and encouraging the oxygen vacancy formation, which has not been fulfilled in conventional chemical/physical approaches. Owing to such distinct chemical