Two-Dimensional Tunneling Memtransistor with Thin-Film Heterostructure for Low-Power Logic-in-Memory Complementary Metal-Oxide Semiconductor.

With the demand for high-performance and miniaturized semiconductor devices continuously rising, the development of innovative tunneling transistors via efficient stacking methods using two-dimensional (2D) building blocks has paramount importance in the electronic industry. Hence, 2D semiconductors with atomically thin geometries hold significant promise for advancements in electronics. In this study, we introduced tunneling memtransistors with a thin-film heterostructure composed of 2D semiconducting MoS2 and WSe2. Devices with the dual function of tuning and memory operation were realized by the gate-regulated modulation of the barrier height at the heterojunction and manipulation of intrinsic defects within the exfoliated nanoflakes using solution processes. Further, our investigation revealed extensive edge defects and four distinct defect types, namely monoselenium vacancies, diselenium vacancies, tungsten vacancies, and tungsten adatoms, in the interior of electrochemically exfoliated WSe2 nanoflakes. Additionally, we constructed complementary metal-oxide semiconductor-based logic-in-memory devices with a small static power in the range of picowatts using the developed tunneling memtransistors, demonstrating a promising approach for next-generation low-power nanoelectronics.

Selenium-alloyed tellurium oxide for amorphous p-channel transistors.

Compared to polycrystalline semiconductors, amorphous semiconductors offer inherent cost-effective, simple and uniform manufacturing. Traditional amorphous hydrogenated Si falls short in electrical properties, necessitating the exploration of new materials. The creation of high-mobility amorphous n-type metal oxides, such as a-InGaZnO (ref. 1), and their integration into thin-film transistors (TFTs) have propelled advancements in modern large-area electronics and new-generation displays2-8. However, finding comparable p-type counterparts poses notable challenges, impeding the progress of complementary metal-oxide-semiconductor technology and integrated circuits9-11. Here we introduce a pioneering design strategy for amorphous p-type semiconductors, incorporating high-mobility tellurium within an amorphous tellurium suboxide matrix, and demonstrate its use in high-performance, stable p-channel TFTs and complementary circuits. Theoretical analysis unveils a delocalized valence band from tellurium 5p bands with shallow acceptor states, enabling excess hole doping and transport. Selenium alloying suppresses hole concentrations and facilitates the p-orbital connectivity, realizing high-performance p-channel TFTs with an average field-effect hole mobility of around 15 cm2 V-1 s-1 and on/off current ratios of 106-107, along with wafer-scale uniformity and long-term stabilities under bias stress and ambient ageing. This study represents a crucial stride towards establishing commercially viable amorphous p-channel TFT technology and complementary electronics in a low-cost and industry-compatible manner.

All-Solution-Processed High-Performance MoS2 Thin-Film Transistors with a Quasi-2D Perovskite Oxide Dielectric.

Assembling solution-processed van der Waals (vdW) materials into thin films holds great promise for constructing large-scale, high-performance thin-film electronics, especially at low temperatures. While transition metal dichalcogenide thin films assembled in solution have shown potential as channel materials, fully solution-processed vdW electronics have not been achieved due to the absence of suitable dielectric materials and high-temperature processing. In this work, we report on all-solution-processedvdW thin-film transistors (TFTs) comprising molybdenum disulfides (MoS2) as the channel and Dion-Jacobson-phase perovskite oxides as the high-permittivity dielectric. The constituent layers are prepared as colloidal solutions through electrochemical exfoliation of bulk crystals, followed by sequential assembly into a semiconductor/dielectric heterostructure for TFT construction. Notably, all fabrication processes are carried out at temperatures below 250 °C. The fabricated MoS2 TFTs exhibit excellent device characteristics, including high mobility (>10 cm2 V-1 s-1) and an on/off ratio exceeding 106. Additionally, the use of a high-k dielectric allows for operation at low voltage (∼5 V) and leakage current (∼10-11 A), enabling low power consumption. Our demonstration of the low-temperature fabrication of high-performance TFTs presents a cost-effective and scalable approach for heterointegrated thin-film electronics.

Boosting the Performance of Photomultiplication-Type Organic Photodiodes by Embedding CsPbBr3 Perovskite Nanocrystals.

In this study, it is demonstrated that CsPbBr3 perovskite nanocrystals (NCs) can enhance the overall performances of photomultiplication-type organic photodiodes (PM-OPDs). The proposed approach enables the ionic-polarizable CsPbBr3 NCs to be evenly distributed throughout the depletion region of Schottky junction interface, allowing the entire trapped electrons within the depletion region to be stabilized, in contrast to previously reported interface-limited strategies. The optimized CsPbBr3 -NC-embedded poly(3-hexylthiophene-diyl)-based PM-OPDs exhibit exceptionally high external quantum efficiency, specific detectivity, and gain-bandwidth product of 2,840,000%, 3.97 × 1015 Jones, and 2.14 × 107  Hz, respectively. 2D grazing-incidence X-ray diffraction analyses and drift-diffusion simulations combined with temperature-dependent J-V characteristic analyses are conducted to investigate the physics behind the success of CsPbBr3 -NC-embedded PM-OPDs. The results show that the electrostatic interactions generated by the ionic polarization of NCs effectively stabilize the trapped electrons throughout the entire volume of the photoactive layer, thereby successfully increasing the effective energy depth of the trap states and allowing efficient PM mechanisms. This study demonstrates how a hybrid-photoactive-layer approach can further enhance PM-OPD when the functionality of inorganic inclusions meets the requirements of the target device.

Unlocking the Potential of Tin-Based Perovskites: Properties, Progress, and Applications in New-Era Electronics.

Electronics have greatly promoted the development of modern society and the exploration of new semiconducting materials with low cost and high mobility continues to attract interest in the advance of next-generation electronic devices. Among emerging semiconductors, the metal-halide perovskite, especially the nontoxic tin (Sn)-based candidates, has recently made breakthroughs in the field of diverse electronic devices due to its excellent charge transport properties and cost-effective large-area deposition capability at low temperatures. To enable a more comprehensive understanding of this emerging research field and promote the development of new-generation perovskite electronics, this review aims to provide an in-depth understanding with the discussion of unique physical properties of Sn-based perovskites and the summarization of recent research progress of Sn-based perovskite field-effect transistors (FETs) and diverse electronic devices. The unique character of negligible ion migration is also discussed, which is fundamentally different from the lead-based counterparts and provides a great prerequisite for device application. The following section highlights the potential broad applications of Sn-perovskite FETs as a competitive and feasible technology. Finally, an outlook and remaining challenges are given to advance the progression of Sn-based perovskite FETs, especially on the origin and solution of stability problems toward high-performance Sn-based perovskite electronics.

Large-Area Printed Oxide Film Sensors Enabling Ultrasensitive and Dual Electrical/Colorimetric Detection of Hydrogen at Room Temperature.

Commercial hydrogen (H2) sensors operate at high temperatures, which increases power consumption and poses a safety risk owing to the flammable nature of H2. Here, a polymer-noble metal-metal oxide film is fabricated using the spin-coating and printing methods to realize a highly sensitive, low-voltage operation, wide-operating-concentration, and near-monoselective H2 sensor at room temperature. The H2 sensors with an optimized thickness of Pd nanoparticles and SnO2 showed an extremely high response of 16,623 with a response time of 6 s and a recovery time of 5 s at room temperature and 2% H2. At the same time, printed flexible sensors demonstrate excellent sensitivity, with a response of 2300 at 2% H2. The excellent sensing performance at room temperature is due to the optimal SnO2 thickness, corresponding to the Debye length and the oxygen and H2 spillover caused by the optimized coverage of the Pd catalyst. Furthermore, multistructures of WO3 and SnO2 films are used to fabricate a new type of dual-signal sensor, which demonstrated simultaneous conductance and transmittance, i.e., color change. This work provides an effective strategy to develop robust, flexible, transparent, and long-lasting H2 sensors through large-area printing processes based on polymer-metal-metal oxide nanostructures.

Large Transconductance of Electrochemical Transistors Based on Fluorinated Donor-Acceptor Conjugated Polymers.

Organic electrochemical transistors (OECTs) have enormous potential for use in biosignal amplifiers, analyte sensors, and neuromorphic electronics owing to their exceptionally large transconductance. However, it is challenging to simultaneously achieve high charge carrier mobility and volumetric capacitance, the two most important figures of merit in OECTs. Herein, a method of achieving high-performance OECT with donor-acceptor conjugated copolymers by introducing fluorine units is proposed. A series of cyclopentadithiophene-benzothiadiazole (CDT-BT) copolymers for use in high-performance OECTs with enhanced charge carrier mobility (from 0.65 to 1.73 cm2·V-1·s-1) and extended volumetric capacitance (from 44.8 to 57.6 F·cm-3) by fluorine substitution is achieved. The increase in the volumetric capacitance of the fluorinated polymers is attributed to either an increase in the volume at which ions can enter the film or a decrease in the effective distance between the ions and polymer backbones. The fluorine substitution increases the backbone planarity of the CDT-BT copolymers, enabling more efficient charge carrier transport. The fluorination strategy of this work suggests the more versatile use of conjugated polymers for high-performance OECTs.

High-Performance Solution-Processed 2D P-Type WSe2 Transistors and Circuits through Molecular Doping.

Semiconducting ink based on 2D single-crystal flakes with dangling-bond-free surfaces enables the implementation of high-performance devices on form-free substrates by cost-effective and scalable printing processes. However, the lack of solution-processed p-type 2D semiconducting inks with high mobility is an obstacle to the development of complementary integrated circuits. Here, a versatile strategy of doping with Br2 is reported to enhance the hole mobility by orders of magnitude for p-type transistors with 2D layered materials. Br2 -doped WSe2 transistors show a field-effect hole mobility of more than 27 cm2  V-1  s-1 , and a high on/off current ratio of ≈107 , and exhibits excellent operational stability during the on-off switching, cycling, and bias stressing testing. Moreover, complementary inverters composed of patterned p-type WSe2 and n-type MoS2 layered films are demonstrated with an ultra-high gain of 1280 under a driving voltage (VDD ) of 7 V. This work unveils the high potential of solution-processed 2D semiconductors with low-temperature processability for flexible devices and monolithic circuitry.

Evaporated nanometer chalcogenide films for scalable high-performance complementary electronics.

The exploration of stable and high-mobility semiconductors that can be grown over a large area using cost-effective methods continues to attract the interest of the electronics community. However, many mainstream candidates are challenged by scarce and expensive components, manufacturing costs, low stability, and limitations of large-area growth. Herein, we report wafer-scale ultrathin (metal) chalcogenide semiconductors for high-performance complementary electronics using standard room temperature thermal evaporation. The n-type bismuth sulfide delivers an in-situ transition from a conductor to a high-mobility semiconductor after mild post-annealing with self-assembly phase conversion, achieving thin-film transistors with mobilities of over 10 cm2 V-1 s-1, on/off current ratios exceeding 108, and high stability. Complementary inverters are constructed in combination with p-channel tellurium device with hole mobilities of over 50 cm2 V-1 s-1, delivering remarkable voltage transfer characteristics with a high gain of 200. This work has laid the foundation for depositing scalable electronics in a simple and cost-effective manner, which is compatible with monolithic integration with commercial products such as organic light-emitting diodes.

Photonic nanostructures mimicking floral epidermis for perovskite solar cells.

Here, we report photonic nanostructures replicated from the adaxial epidermis of flower petals onto light-polymerized coatings using low-cost nanoimprint lithography at ambient temperature. These multifunctional nanocoatings are applied to confer enhanced light trapping, water repellence, and UV light and environmental moisture protection features in perovskite solar cells. The former feature helps attain a maximum power conversion efficiency of 24.61% (21.01% for the reference cell) without any additional device optimization. Added to these merits, the nanocoatings also enable stable operation under AM 1.5G and UV light continuous illumination or in real-world conditions. Our engineering approach provides a simple way to produce multifunctional nanocoatings optimized by nature's wisdom.

Sn-Based Perovskite Halides for Electronic Devices.

Because of its less toxicity and electronic structure analogous to that of lead, tin halide perovskite (THP) is currently one of the most favorable candidates as an active layer for optoelectronic and electric devices such as solar cells, photodiodes, and field-effect transistors (FETs). Promising photovoltaics and FETs performances have been recently demonstrated because of their desirable electrical and optical properties. Nevertheless, THP's easy oxidation from Sn2+ to Sn4+ , easy formation of tin vacancy, uncontrollable film morphology and crystallinity, and interface instability severely impede its widespread application. This review paper aims to provide a basic understanding of THP as a semiconductor by highlighting the physical structure, energy band structure, electrical properties, and doping mechanisms. Additionally, the key chemical instability issues of THPs are discussed, which are identified as the potential bottleneck for further device development. Based on the understanding of the THPs properties, the key recent progress of THP-based solar cells and FETs is briefly discussed. To conclude, current challenges and perspective opportunities are highlighted.

High-performance hysteresis-free perovskite transistors through anion engineering.

Despite the impressive development of metal halide perovskites in diverse optoelectronics, progress on high-performance transistors employing state-of-the-art perovskite channels has been limited due to ion migration and large organic spacer isolation. Herein, we report high-performance hysteresis-free p-channel perovskite thin-film transistors (TFTs) based on methylammonium tin iodide (MASnI3) and rationalise the effects of halide (I/Br/Cl) anion engineering on film quality improvement and tin/iodine vacancy suppression, realising high hole mobilities of 20 cm2 V-1 s-1, current on/off ratios exceeding 107, and threshold voltages of 0 V along with high operational stabilities and reproducibilities. We reveal ion migration has a negligible contribution to the hysteresis of Sn-based perovskite TFTs; instead, minority carrier trapping is the primary cause. Finally, we integrate the perovskite TFTs with commercialised n-channel indium gallium zinc oxide TFTs on a single chip to construct high-gain complementary inverters, facilitating the development of halide perovskite semiconductors for printable electronics and circuits.

Sodium Incorporation for Enhanced Performance of Two-Dimensional Sn-Based Perovskite Transistors.

Two-dimensional metal halide perovskites (2D MHPs) are promising candidates for transistor channel materials because of their high mobility in the lateral direction; however, Sn-based 2D MHPs exhibit poor film quality and oxidation stability. Here, we report a simple method to improve the performance and stability of 2D MHP transistors by incorporating sodium iodide (NaI) additives. By adding 1 vol % NaI (Na1), the transistors with phenethylammonium tin iodide (PEA2SnI4) exhibited reduced dual-sweep hysteresis, robust bias stability, and larger hole mobility (2.13 cm2 V-1 s-1) than that of a pristine device (0.39 cm2 V-1 s-1). Improvements in the film quality, such as increased grain size, crystallinity, and better film coverage, were observed in the PEA2SnI4:NaI film. In addition, NaI effectively passivated the iodine vacancies at the grain boundaries, thereby suppressing the defects.

Engineering Copper Iodide (CuI) for Multifunctional p-Type Transparent Semiconductors and Conductors.

Developing transparent p-type semiconductors and conductors has attracted significant interest in both academia and industry because metal oxides only show efficient n-type characteristics at room temperature. Among the different candidates, copper iodide (CuI) is one of the most promising p-type materials because of its widely adjustable conductivity from transparent electrodes to semiconducting layers in transistors. CuI can form thin films with high transparency in the visible light region using various low-temperature deposition techniques. This progress report aims to provide a basic understanding of CuI-based materials and recent progress in the development of various devices. The first section provides a brief introduction to CuI with respect to electronic structure, defect states, charge transport physics, and overviews the CuI film deposition methods. The material design concepts through doping/alloying approaches to adjust the optoelectrical properties are also discussed in the first section. The following section presents recent advances in state-of-the-art CuI-based devices, including transparent electrodes, thermoelectric devices, p-n diodes, p-channel transistors, light emitting diodes, and solar cells. In conclusion, current challenges and perspective opportunities are highlighted.

Highly Reliable Organic Field-Effect Transistors with Molecular Additives for a High-Performance Printed Gas Sensor.

Organic semiconductors (OSCs) are promising sensing materials for printed flexible gas sensors. However, OSCs are unstable in the humid air, which limits the realization of gas sensors for multiple usages. In this paper, we report a facile and effective way to improve the air stability of an OSC film to realize multiple reversibly used printed gas sensors by adding molecular additives. The tetracyanoquinodimethane (TCNQ) or 4-aminobenzonitrile (ABN) additives effectively prevent adsorption of moisture from the air on the OSC layer, thereby providing a stable gas sensor operation. The organic field-effect transistor (OFET)-based indacenodithiophene-co-benzothiadiazole with TCNQ or ABN shows highly reliable ammonia (NH3) gas sensing up to 10 ppm in air, with 23.14% sensitivity, and the gas sensor signal can recover up to 100%. In particular, the stability of gas detection is greatly improved by the additives, which can be performed in the air for 16 days. The result indicates that the elimination of moisture trapped in OSCs with molecule additives is critical in the improvement of device air/operational stabilities and the achievement of high-performance OFET-based gas sensors.

1D-CoSe2 nanoarray: a designed structure for efficient hydrogen evolution and symmetric supercapacitor characteristics.

Direct growth of self-supported one-dimensional (1D) nanorod arrays on conducting substrates is highly attractive for electrocatalysis, due to their unique shape, size, and length. In this work, a facile and simple two-step method was employed to synthesize 1D-CoSe2 nanoarrays on titanium (Ti) foil via a wet chemical ion-exchange approach. The as-synthesized 1D-CoSe2 nanoarrays were directly used as electrode materials for hydrogen evolution reaction and supercapacitors. As an electrocatalyst, the optimized 1D-CoSe2(tex-48 h) nanoarray exhibits excellent hydrogen evolution properties with a small Tafel slope of 78 mV dec-1, low overpotentials of 41 mV@1 mA cm-2 and 216 mV@10 mA cm-2, and extended robust performance for 25 h. Moreover, for a symmetric device, it delivers a maximum specific capacitance of 152 F g-1 at 0.5 A g-1 and a better energy density of 21.1 W h kg-1 at a power density of 0.5 kW kg-1. Also, the symmetric device capacity retention behavior achieves ∼96.8% of the initial result after 5000 cycles, revealing the good stability of the electrode. Our findings offer a new way to further the development of high-performance energy devices.

High-performance p-channel transistors with transparent Zn doped-CuI.

'Ideal' transparent p-type semiconductors are required for the integration of high-performance thin-film transistors (TFTs) and circuits. Although CuI has recently attracted attention owing to its excellent opto-electrical properties, solution processability, and low-temperature synthesis, the uncontrolled copper vacancy generation and subsequent excessive hole doping hinder its use as a semiconductor material in TFT devices. In this study, we propose a doping approach through soft chemical solution process and transparent p-type Zn-doped CuI semiconductor for high-performance TFTs and circuits. The optimised TFTs annealed at 80 °C exhibit a high hole mobility of over 5 cm2 V-1 s-1 and high on/off current ratio of ~107 with good operational stability and reproducibility. The CuI:Zn semiconductors show intrinsic advantages for next-generation TFT applications and wider applications in optoelectronics and energy conversion/storage devices. This study paves the way for the realisation of transparent, flexible, and large-area integrated circuits combined with n-type metal-oxide semiconductor.

High-Performance and Reliable Lead-Free Layered-Perovskite Transistors.

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.