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Two-dimensional (2D) nanocrystals are promising for optoelectronic and microelectronic technologies. However, the performance of 2D nanocrystal light-emitting diodes (LEDs) remains limited. Here, exciton dynamics are rationally controlled by both shell engineering and device engineering, obtaining colloidal quantum well LEDs (CQW-LEDs) with superior performance. The formation of CQW films on charge transport layers shows an excellent photoluminescence quantum yield of 76.63%. An unreported relationship among Auger lifetime, electron confinement energy, and external quantum efficiency (EQE) in 2D nanocrystal devices is directly observed. The optimized CQW-LEDs possess a maximum power efficiency of 6.04 lm W−1 and a current efficiency of 9.20 cd A−1, setting record efficiencies for 2D nanocrystal red LEDs. Additionally, a remarkable EQE of 13.43% has been achieved, accompanied by an exceptionally low efficiency roll-off. Significantly, EQE for flexible CQW-LEDs is 42-fold higher than the previous best results. Furthermore, active-matrix CQW-LEDs on printed circuit boards are developed. The findings not only unlock new possibilities for controlling exciton dynamics but also provide an alternative strategy to achieve high-performance 2D nanocrystal based applications. [ABSTRACT FROM AUTHOR]

In this paper, we developed a new method to construct flexible fully-printed all-carbon thin film transistors (TFTs) with excellent properties and highly sensitive ammonia (NH3) sensors via aerosol jet printing. Here, sorted semiconducting single-walled carbon nanotubes (sc-SWCNTs), carboxyl-functionalized single-walled carbon nanotubes (P3 SWCNTs) and printed ion gels were chosen as channel materials, printed source, drain and side-gate electrodes, and dielectric layers. Flexible printed side-gate TFTs showed high on/off ratios (∼106), good mobility (up to 9.8 cm2 V−1 s−1), low hysteresis and small subthreshold swings (∼80 mV dec−1) at gate voltages of ±1 V. As-prepared TFTs exhibited an extremely high response to NH3 (up to 346.73% within 11 s) with good selectivity, ultralow limit of detection (LOD) (21.35 ppb) and low power consumption (0.49 nW) at room temperature due to the strong adsorption and enrichment of NH3 gas by ionic liquids (ILs) in the ion gels and the signal amplification of printed ion-gel TFTs. Furthermore, all devices can withstand 10 000 times bending with a radius of 5 mm, displaying good mechanical flexibility due to the high mechanical properties of carbon nanotubes. [ABSTRACT FROM AUTHOR]

An integrated study including petrography, mineral chemistry, metamorphic P–T path modelling, and zircon U–Pb dating was conducted on a granitic gneiss and enclosed eclogite from South Dulan, North Qaidam UHP (ultrahigh-pressure) belt. The result shows that the granitic gneiss underwent a clockwise P–T path with a peak-P stage at 655–745°C, 30–34 kbar, and a subsequent peak-T stage at 815–870°C, 14–18 kbar, which is similar to the P–T estimates reported for coesite-bearing continental-type eclogites in this region. The enclosed eclogite resembles an olivine–pyroxene-rich cumulate in Qaidam block. It has a similar prograde P–T path with the country gneiss and experienced a peak-P stage of 682–748°C at 27–34 kbar. Zircon U–Pb dating yields an eclogite-facies metamorphic age of 447 ± 2 Ma for the granitic gneiss and 445 ± 6 Ma for the enclosed eclogite. These ages agree with metamorphic ages obtained from paragneisses (427–439 Ma), coesite-bearing continental-type eclogites (430–451 Ma), and UHPM (ultrahigh-pressure metamorphic) oceanic crust–mantle sequence (440–445 Ma) from South Dulan, as well as UHP eclogites, garnet peridotite, and gneisses from other units (460–420 Ma) within this belt reported by others. Similar metamorphic ages as well as P–T evolution documented in gneisses and intercalated eclogites imply that both rocks experienced a coeval UHP event. Summarizing all the published geochronology data, we argue that the North Qaidam UHP belt was mainly formed by continental deep subduction at ~460 to ~420 Ma. The UHPM oceanic crust-mantle sequence in South Dulan may represent oceanic lithosphere in the transition zone between oceanic and continental crust, which was dragged upward by the exhumed continental rocks after break-off of the dense oceanic crust. [ABSTRACT FROM PUBLISHER]

Development of large-area, low-cost, low-voltage, low-power consumption, flexible high-performance printed carbon nanotube thin-film transistors (TFTs) is helpful to promote their future applications in sensors and biosensors, wearable electronics, and the Internet of things. In this work, low-voltage, flexible printed carbon nanotube TFTs with a large-area and low-cost fabrication process were successfully constructed using ultrathin (∼3.6 nm) AlO x thin films formed by plasma oxidation of aluminum as dielectrics and screen-printed silver electrodes as contact electrodes. The as-prepared bottom-gate/bottom-contact carbon nanotube TFTs exhibit a low leakage current (∼10 -10 A), a high charge carrier mobility (up to 9.9 cm 2 V -1 s -1 ), high on/off ratios (higher than 10 5 ), and small subthreshold swings (80-120 mV/dec) at low operation voltages (from -1.5 to 1 V). At the same time, printed carbon nanotube TFTs showed a high response (Δ R / R = 99.6%) to NO 2 gas even at 16 ppm with a faster response and recovery speed (∼8 s, exposure to 0.5 ppm NO 2 ), a lower detection limit (0.069 ppm NO 2 ), and a low power consumption (0.86 μW, exposure to 16 ppm NO 2 ) at a gate voltage of 0.2 V at room temperature. Moreover, the printed carbon nanotube devices exhibited excellent mechanical flexibility and bias stress stability after 12,000 bending cycles at a radius of 5 mm and a bias stress test for 7200 s at a gate voltage of ±1 V, which originated from the ultrathin and compact AlO x dielectric and the super adhesion force between screen-printed silver electrodes and polyethylene terephthalate substrates.