The electronic functionalities of metal oxides comprise conductors, semiconductors, and insulators. Metal oxides have attracted great interest for construction of large‐area electronics, particularly ...thin‐film transistors (TFTs), for their high optical transparency, excellent chemical and thermal stability, and mechanical tolerance. High‐permittivity (κ) oxide dielectrics are a key component for achieving low‐voltage and high‐performance TFTs. With the expanding integration of complementary metal oxide semiconductor transistors, the replacement of SiO2 with high‐κ oxide dielectrics has become urgently required, because their provided thicker layers suppress quantum mechanical tunneling. Toward low‐cost devices, tremendous efforts have been devoted to vacuum‐free, solution processable fabrication, such as spin coating, spray pyrolysis, and printing techniques. This review focuses on recent progress in solution processed high‐κ oxide dielectrics and their applications to emerging TFTs. First, the history, basics, theories, and leakage current mechanisms of high‐κ oxide dielectrics are presented, and the underlying mechanism for mobility enhancement over conventional SiO2 is outlined. Recent achievements of solution‐processed high‐κ oxide materials and their applications in TFTs are summarized and traditional coating methods and emerging printing techniques are introduced. Finally, low temperature approaches, e.g., ecofriendly water‐induced, self‐combustion reaction, and energy‐assisted post treatments, for the realization of flexible electronics and circuits are discussed.
High‐permittivity (κ) dielectrics play a crucial role in realizing low‐power‐consumption and high‐performance transistors and circuits. Benefiting from the unique characteristics of low‐cost solution routes, recent progress in the development of solution‐processed oxide dielectrics and their applications in emerging transistors is summarized. With the raising popularity of flexible electronics in the foreseeable future, novel low‐temperature techniques are further highlighted.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
For at least the past ten years printed electronics has promised to revolutionize our daily life by making cost‐effective electronic circuits and sensors available through mass production techniques, ...for their ubiquitous applications in wearable components, rollable and conformable devices, and point‐of‐care applications. While passive components, such as conductors, resistors and capacitors, had already been fabricated by printing techniques at industrial scale, printing processes have been struggling to meet the requirements for mass‐produced electronics and optoelectronics applications despite their great potential. In the case of logic integrated circuits (ICs), which constitute the focus of this Progress Report, the main limitations have been represented by the need of suitable functional inks, mainly high‐mobility printable semiconductors and low sintering temperature conducting inks, and evoluted printing tools capable of higher resolution, registration and uniformity than needed in the conventional graphic arts printing sector.
Solution‐processable polymeric semiconductors are the best candidates to fulfill the requirements for printed logic ICs on flexible substrates, due to their superior processability, ease of tuning of their rheology parameters, and mechanical properties. One of the strongest limitations has been mainly represented by the low charge carrier mobility (μ) achievable with polymeric, organic field‐effect transistors (OFETs). However, recently unprecedented values of μ ∼ 10 cm2/Vs have been achieved with solution‐processed polymer based OFETs, a value competing with mobilities reported in organic single‐crystals and exceeding the performances enabled by amorphous silicon (a‐Si). Interestingly these values were achieved thanks to the design and synthesis of donor‐acceptor copolymers, showing limited degree of order when processed in thin films and therefore fostering further studies on the reason leading to such improved charge transport properties. Among this class of materials, various polymers can show well balanced electrons and holes mobility, therefore being indicated as ambipolar semiconductors, good environmental stability, and a small band‐gap, which simplifies the tuning of charge injection. This opened up the possibility of taking advantage of the superior performances offered by complementary “CMOS‐like” logic for the design of digital ICs, easing the scaling down of critical geometrical features, and achieving higher complexity from robust single gates (e.g., inverters) and test circuits (e.g., ring oscillators) to more complete circuits.
Here, we review the recent progress in the development of printed ICs based on polymeric semiconductors suitable for large‐volume micro‐ and nano‐electronics applications. Particular attention is paid to the strategies proposed in the literature to design and synthesize high mobility polymers and to develop suitable printing tools and techniques to allow for improved patterning capability required for the down‐scaling of devices in order to achieve the operation frequencies needed for applications, such as flexible radio‐frequency identification (RFID) tags, near‐field communication (NFC) devices, ambient electronics, and portable flexible displays.
A brief overview of recent advances in and perspectives for printed electronic devices and circuits, mainly focusing on those based on unipolar or ambipolar polymer semiconductors is presented. The most promising strategies for realizing high‐performance complementary and ambipolar integrated circuits and recent progress toward these approaches are critically reviewed.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The gate dielectric layer is an essential element of field‐effect transistors (FETs), large area integrated circuits, and various application electronics. Beyond basic insulation between the ...semiconductor layer and gate electrode, FET performance largely depends on the capacitance of the chosen insulator layer properties. Recent functional devices developments require new functionalities, such as high mechanical flexibility and stretchability in addition to basic insulating and physical properties. This review focuses on recent developments of high‐capacitance polymer gate dielectric materials and their application for low‐voltage flexible FETs. The fundamental principles and components of transistors are discussed briefly, then the underlying concepts for gate dielectrics and the mechanisms for polymer dielectric properties, such as capacitance control, leakage current formation in dielectric polymer films, and patternability, are described. Strategic approaches to achieve high capacitance based on low‐k dielectric materials, and the development and use of high‐capacitance polymers and hybrid polymer gate dielectrics in the context of emerging transistors on flexible substrates are also discussed.
The recent developments on high‐capacitance polymer gate dielectrics for low‐voltage flexible organic field‐effect transistors are reviewed. Fundamental transistor principles and components are briefly described, then recent approaches to achieve high capacitance based on low‐k dielectrics, and the use of developed high‐capacitance polymers and hybrid polymer gate dielectrics for emerging flexible transistors are discussed.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Studies on printable semiconductors and technologies have increased rapidly over recent decades, pioneering novel applications in many fields, such as energy, sensing, logic circuits, and information ...displays. The newest display technologies are already turning to metal oxide semiconductors, i.e., indium gallium zinc oxide, for the improvements needed to drive active matrix organic light‐emitting diodes. Convenience and portability will be realized with flexible and wearable displays in the future. This report summarizes recent progress on the development of solution‐processed thin film transistors, especially those deposited at low temperatures for next‐generation flexible smart displays. The first part provides an overview on the history and current status of displays. Then, recent advances in state‐of‐the‐art solution‐processed transistors based on different semiconductors are presented, including metal oxides, organic materials, perovskites, and carbon nanotubes. Finally, conclusions are drawn and the remaining challenges and future perspectives are discussed.
Semiconductor evolution has greatly promoted the development of high‐end displays over the past decades. Benefiting from the unique characteristics of low‐cost solution routes, recent progress in the development of solution‐processed thin film transistors (metal oxides, organics, carbon nanotubes, and perovskite) and their applications in next‐generation flexible smart displays are summarized. The challenges and prospectives for further development are also highlighted.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
While organic electronics is mostly dominated by light‐emitting diodes, photovoltaic cells and transistors, optoelectronics properties peculiar to organic semiconductors make them interesting ...candidates for the development of innovative and disruptive applications also in the field of light signal detection. In fact, organic‐based photoactive media combine effective light absorption in the region of the spectrum from ultraviolet to near‐infrared with good photogeneration yield and low‐temperature processability over large areas and on virtually every substrate, which might enable innovative optoelectronic systems to be targeted for instance in the field of imaging, optical communications or biomedical sensing.
In this review, after a brief resume of photogeneration basics and of devices operation mechanisms, we offer a broad overview of recent progress in the field, focusing on photodiodes and phototransistors. As to the former device category, very interesting values for figures of merit such as photoconversion efficiency, speed and minimum detectable signal level have been attained, and even though the simultaneous optimization of all these relevant parameters is demonstrated in a limited number of papers, real applications are within reach for this technology, as it is testified by the increasing number of realizations going beyond the single‐device level and tackling more complex optoelectronic systems. As to phototransistors, a more recent subject of study in the framework of organic electronics, despite a broad distribution in the reported performances, best photoresponsivities outperform amorphous silicon‐based devices. This suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo‐sensor, opto‐isolator, image sensor, optically controlled phase shifter, and opto‐electronic switch and memory.
Organic‐based photoactive media combine effective light absorption with good photogeneration yield and low‐temperature processability over large areas, which may enable innovative light detectors suitable for optoelectronic systems in the field of imaging, optical communications or biomedical sensing. A broad overview of recent progress in the field is provided with focus on photodiodes and phototransistors.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The doping of semiconductors plays a critical role in improving the performance of modern electronic devices by precisely controlling the charge carrier density. However, the absence of a stable ...doping method for p‐type oxide semiconductors has severely restricted the development of metal oxide‐based transparent p–n junctions and complementary circuits. Here, an efficient and stable doping process for p‐type oxide semiconductors by using molecule charge transfer doping with tetrafluoro‐tetracyanoquinodimethane (F4TCNQ) is reported. The selections of a suitable dopant and geometry play a crucial role in the charge‐transfer doping effect. The insertion of a F4TCNQ thin dopant film (2–7 nm) between a Au source‐drain electrode and solution‐processed p‐type copper oxide (CuxO) film in bottom‐gate top‐contact thin‐film transistors (TFTs) provides a mobility enhancement of over 20‐fold with the desired threshold voltage adjustment. By combining doped p‐type CuxO and n‐type indium gallium zinc oxide TFTs, a solution‐processed transparent complementary metal‐oxide semiconductor inverter is demonstrated with a high gain voltage of 50. This novel p‐doping method is expected to accelerate the development of high‐performance and reliable p‐channel oxide transistors and has the potential for widespread applications.
Molecule charge transfer p‐doping for p‐channel copper oxide (CuxO) thin‐film transistors (TFTs) is demonstrated for the first time with a dramatically improved hole mobility of over 20‐fold without sacrificing other opto‐electrical parameters. The high doping efficiency and high‐performance complementary inverter provide new opportunities for high‐performance p‐channel TFTs and circuit realization.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Organic field-effect transistors (OFETs) are promising for numerous potential applications but suffer from poor charge injection, such that their performance is severely limited. Recent efforts in ...lowering contact resistance have led to significantly improved field-effect mobility of OFETs, up to 100 times higher, as the results of careful choice of contact materials and/or chemical treatment of contact electrodes. Here we review the innovative developments of contact engineering and focus on the mechanisms behind them. Further improvement toward Ohmic contact can be expected along with the rapid advance in material research, which will also benefit other organic and electronic devices.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Perovskites have been intensively investigated for their use in solar cells and light‐emitting diodes. However, research on their applications in thin‐film transistors (TFTs) has drawn less attention ...despite their high intrinsic charge carrier mobility. In this study, the universal approaches for high‐performance and reliable p‐channel lead‐free phenethylammonium tin iodide TFTs are reported. These include self‐passivation for grain boundary by excess phenethylammonium iodide, grain crystallization control by adduct, and iodide vacancy passivation through oxygen treatment. It is found that the grain boundary passivation can increase TFT reproducibility and reliability, and the grain size enlargement can hike the TFT performance, thus, enabling the first perovskite‐based complementary inverter demonstration with n‐channel indium gallium zinc oxide TFTs. The inverter exhibits a high gain over 30 with an excellent noise margin. This work aims to provide widely applicable and repeatable methods to make the gate more open for intensive efforts toward high‐performance printed perovskite TFTs.
Universal approaches for high‐performance and reliable p‐channel lead‐free phenethylammonium tin iodide perovskite‐based transistors are developed, including self‐passivation for grain boundaries by excess phenethylammonium iodide, crystallization control by adducts, and iodide vacancy passivation through oxygen treatment. The first complementary inverter is also demonstrated combined with n‐channel indium gallium zinc oxide transistors.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
2D metal halide perovskites are attracting great interest for their diverse applications owing to their intrinsic superior stability compared to their 3D counterparts; however, their device ...performance is limited by insufficient charge transport because of the insulating bulky organic ligands. Electrical doping is a direct and efficient method for improving the electrical properties of emerging semiconductors; however, its feasibility and mechanism remain elusive in metal halide perovskites. To clarify this issue, in this study, diverse organic/inorganic molecules are deposited on a typical phenylethyl ammonium tin iodide ((PEA)2SnI4) perovskite by constructing a heterojunction. In addition, the variations in the electrical performance of the perovskite semiconductor are monitored. The low work function of the dopant molecules enables the spontaneous electron transfer from the perovskite, resulting in the p‐doping effect on the perovskite host, which is verified by a series of characterization methods. The efficient charge transfer without deterioration of the perovskite microstructure improves the Hall mobility up to 100 cm2 V−1 s−1. Therefore, this work demonstrates the high doping efficiency of halide perovskites using a simple molecular charge transfer approach and provides a new opportunity for employing 2D perovskites in high‐efficiency optoelectronic devices.
This study demonstrates the high doping efficiency of halide perovskites using a simple molecular charge transfer approach and provides a new opportunity for employing 2D perovskites in high‐efficiency optoelectronic devices. A thin p‐type dopant layer, tetrafluoro‐tetracyanoquinodimethane and molybdenum trioxide, deposited using thermal evaporation improves the control of damage‐free electronic doping. The efficient charge transfer without deterioration of the perovskite microstructure improves the Hall mobility up to 100 cm2 V−1 s−1.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Organic field‐effect transistors (OFETs) are the central building blocks of organic electronics, but still suffer from low performance and manufacturing difficulties. This is due in part to the ...absence of doping, which is mostly excluded from OFET applications for the concern about uncontrollable dopant diffusion. Doping enabled the modern semiconductor industry to build essential components like Ohmic contacts and P–N junctions, empowering devices to function as designed. Recent breakthroughs in organic semiconductors and doping techniques demonstrated that doping can also be a key enabler for high‐performance OFETs. However, the knowledge of organic doping remains limited particularly for OFET use. Therefore, this review addresses OFET doping from a device perspective. The paper overviews doping basics and roles in advanced complementary technologies. These fundamentals help to understand why and how doping provides the desired transistor characteristics. Typical OFETs without doping are discussed, with consideration for operating principle and problems caused by the absence of doping. Achievements for channel, contact, and overall doping are also examined to clarify the corresponding doping roles. Finally, doping mechanisms, techniques, and dopants associated with OFET applications are reviewed. This paper promotes fundamental understanding of OFET doping for the development of high‐performance OFETs with doped components.
Doping specifically for organic transistor applications from a device perspective is reviewed. Doping fundamentals, various doping roles in transistors, different operating principles, relevant issues caused by the absence of doping in typical organic transistors, organic transistor doping achievements to date, doping mechanisms, techniques, and dopants are systematically discussed.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
PDF