Jin Jang

Bio: Jin Jang is an academic researcher from Kyung Hee University. The author has contributed to research in topics: Thin-film transistor & Amorphous silicon. The author has an hindex of 56, co-authored 931 publications receiving 14964 citations. Previous affiliations of Jin Jang include Chinese Academy of Sciences & LG Electronics.

A high efficiency solution processed polymer inverted triple-junction solar cell exhibiting a power conversion efficiency of 11.83%

Abstract: High efficiency, solution-deposited polymer inverted double- and triple-junction solar cells are demonstrated. The devices are composed of three distinctive photosensitive materials in three distinct subcells, with minimal absorption spectral overlap, and with a bandgap ranging from 1.3 eV to 1.82 eV. A transparent hybrid inorganic organic mixture was introduced as an interconnecting layer to optically and physically connect the subcells. Accordingly, a power conversion efficiency of 10.39% was attained for the double-junction cell and a record high of 11.83% was obtained for the triple-junction cell.

High-performance solution processed oxide TFT with aluminum oxide gate dielectric fabricated by a sol–gel method

Abstract: We have studied the fabrication of solution processed aluminum-oxide (AlOx) gate dielectric at the maximum process temperature of 300 °C for a solution based zinc-tin-oxide (ZTO) thin-film-transistor (TFT). An AlOx layer was spin-coated from a solution of aluminum chloride (AlCl3) and then annealed at 300 °C for 1 h. The breakdown electrical field and leakage current density of the AlOx were found to be ∼4 MV cm−1 and 63 μA cm−2 at 1 MV cm−1, respectively. The ZTO layer was prepared by spin-coating or inkjet printing as an active layer of the TFT with AlOx gate dielectric and then annealed at 300 °C for 1 h. The TFT made using spin coating exhibited the field-effect mobility of 33 cm2 V−1s−1 in the saturation region, a gate swing of 96 mV dec.−1 and a threshold voltage of ∼1.2 V and the inkjet printed TFT showed a field-effect mobility of 24 cm2 V−1s−1.

Electric-field-enhanced crystallization of amorphous silicon

Abstract: Thin films of polycrystalline silicon are of great importance for large-area electronic applications, providing, for example, the switching electronics in many flat-panel displays. Polycrystalline silicon is typically produced by annealing films of amorphous silicon1 that have been deposited from the vapour phase, and much research is focused on lowering the crystallization temperature. It is known that the solid-phase crystallization temperature of amorphous silicon can be reduced by the addition of certain metals2, such as nickel3. Here we show that the rate at which this metal-induced crystallization takes place is markedly enhanced in the presence of an electric field. For example, the crystallization time at 500 °C decreases from 25 hours to 10 minutes on application of a modest (80 V cm−1) electric field. No residual amorphous phase can be detected in the films. A thin-film transistor fabricated from such a film exhibits a field-effect mobility of 58 cm2 V−1 s−1, thereby demonstrating the practical utility of these materials.

Light induced instabilities in amorphous indium–gallium–zinc–oxide thin-film transistors

Abstract: The effect of exposure to ultraviolet radiation on the characteristics of amorphous indium–gallium–zinc–oxide thin-film transistors (TFTs) fabricated by sputtering is investigated. After illumination with 1.5 mW cm−2 of 365 nm radiation, in the absence of any bias stress, a persistent negative shift in the characteristics is observed in the dark. The magnitude of the shift increases with exposure time, saturating after about 10 min. Under these conditions the subthreshold exhibits a rigid shift of around 3.6 V and 7.5 V for TFTs with an active layer thickness of 20 nm and 50 nm, respectively. The shift in the dark increases (decreases) when a negative (positive) bias stress is applied under illumination. The instability behavior caused by exposure to light, in the absence of any bias stress, can be explained on the basis of ionization of neutral oxygen vacancies.

Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors

Abstract: Transparent electronic devices formed on flexible substrates are expected to meet emerging technological demands where silicon-based electronics cannot provide a solution. Examples of active flexible applications include paper displays and wearable computers1. So far, mainly flexible devices based on hydrogenated amorphous silicon (a-Si:H)2,3,4,5 and organic semiconductors2,6,7,8,9,10 have been investigated. However, the performance of these devices has been insufficient for use as transistors in practical computers and current-driven organic light-emitting diode displays. Fabricating high-performance devices is challenging, owing to a trade-off between processing temperature and device performance. Here, we propose to solve this problem by using a novel semiconducting material—namely, a transparent amorphous oxide semiconductor from the In-Ga-Zn-O system (a-IGZO)—for the active channel in transparent thin-film transistors (TTFTs). The a-IGZO is deposited on polyethylene terephthalate at room temperature and exhibits Hall effect mobilities exceeding 10 cm2 V-1 s-1, which is an order of magnitude larger than for hydrogenated amorphous silicon. TTFTs fabricated on polyethylene terephthalate sheets exhibit saturation mobilities of 6–9 cm2 V-1 s-1, and device characteristics are stable during repetitive bending of the TTFT sheet.

Diamond-like amorphous carbon

Abstract: Diamond-like carbon (DLC) is a metastable form of amorphous carbon with significant sp3 bonding. DLC is a semiconductor with a high mechanical hardness, chemical inertness, and optical transparency. This review will describe the deposition methods, deposition mechanisms, characterisation methods, electronic structure, gap states, defects, doping, luminescence, field emission, mechanical properties and some applications of DLCs. The films have widespread applications as protective coatings in areas, such as magnetic storage disks, optical windows and micro-electromechanical devices (MEMs).

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

Abstract: Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed and p-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n-type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution-processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p-type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n- and p-type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n- and p-type oxide transistors as well as the fabrication of CMOS devices with and on paper.

Synthesis of Light-Emitting Conjugated Polymers for Applications in Electroluminescent Devices

Abstract: A review was presented to demonstrate a historical description of the synthesis of light-emitting conjugated polymers for applications in electroluminescent devices. Electroluminescence (EL) was first reported in poly(para-phenylene vinylene) (PPV) in 1990 and researchers continued to make significant efforts to develop conjugated materials as the active units in light-emitting devices (LED) to be used in display applications. Conjugated oligomers were used as luminescent materials and as models for conjugated polymers in the review. Oligomers were used to demonstrate a structure and property relationship to determine a key polymer property or to demonstrate a technique that was to be applied to polymers. The review focused on demonstrating the way polymer structures were made and the way their properties were controlled by intelligent and rational and synthetic design.

Efficient organic solar cells processed from hydrocarbon solvents

Abstract: Organic solar cells have desirable properties, including low cost of materials, high-throughput roll-to-roll production, mechanical flexibility and light weight. However, all top-performance devices are at present processed using halogenated solvents, which are environmentally hazardous and would thus require expensive mitigation to contain the hazards. Attempts to process organic solar cells from non-halogenated solvents lead to inferior performance. Overcoming this hurdle, here we present a hydrocarbon-based processing system that is not only more environmentally friendly but also yields cells with power conversion efficiencies of up to 11.7%. Our processing system incorporates the synergistic effects of a hydrocarbon solvent, a novel additive, a suitable choice of polymer side chain, and strong temperature-dependent aggregation of the donor polymer. Our results not only demonstrate a method of producing active layers of organic solar cells in an environmentally friendly way, but also provide important scientific insights that will facilitate further improvement of the morphology and performance of organic solar cells. The processing of high-performance organic solar cells usually requires environmentally hazardous solvents. Now, hydrocarbon-based processing is shown to achieve relatively high performance in a more environmentally friendly way.