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Recently, lead-free double perovskites of Cs2AgBiBr6 have attracted worldwide attention as a promising candidate for eco-friendly photovoltaics because of their intrinsic environmental stability and highly desired low toxicity in comparison with conventional lead halide counterparts. However, their power conversion efficiency (PCE) is still far lower than that of lead halide perovskites, which is mainly associated with their poor quality films. Herein, we report a facile process via precursor engineering based on the BiBr3(DMSO)2 adduct solution to produce high-coverage and smooth Cs2AgBiBr6 films with large grains. As a result, the as-constructed planar solar cells deliver a champion PCE of 0.73%, which exhibits an enhancement of over 40% in PCE compared to that of the control sample, suggesting their potential to be applied in lead-free bismuth-based optoelectronic devices. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) is recognized as a promising substitute for the currently used Si for exploring robust pressure sensors with desired high sensitivities and excellent abilities to serve under harsh work conditions. In the present work, we reported the giant piezoresistance effect of p-type 3C-SiC nanowires with B dopants, which were synthesized by catalyst-assisted pyrolysis of polysilazane. The transverse electromechanical properties of SiC nanowires were investigated at loading forces applied using a conductive atomic force microscopy (C-AFM) tip. The resistances of the as-synthesized SiC nanowires exhibit an increase with the increase of compressed stresses at the same bias voltages, representing their negative piezoresistance behaviors. The measured negative piezoresistance coefficient π[11̅0] of the nanowire fell in the range of −8.83 to −103.42 × 10−11 Pa−1 as the applied loading forces ranged from 51.7 to 181.0 nN. The giant gauge factor (GF) could be up to −620.5, which was enhanced by more than 10 times compared to the highest ever reported for SiC nanostructures. [ABSTRACT FROM AUTHOR]

To achieve precision instrumentation and accurate measurement, there is increasing need for pressure sensors to be well serviced in harsh environments. We report, for the first time, piezoresistance in single-crystalline Si3N4 nanobelts by conductive atomic force microscopy (C-AFM). The transverse electromechanical properties of the Si3N4 nanobelt were investigated under various loading forces applied by the C-AFM tip. The calculated transverse piezoresistance coefficient π[12̅0] of the nanobelt was in the range of 2.2 to 8.8 × 10−11 Pa−1 under the applied loading forces ranging from 25.6 to 135.3 nN. The relationship between the piezoresistance coefficients and the applied forces was almost linear. Significant and linear decreases in nanobelt resistance with increasing loading forces were observed, which exhibited a variation of ∼3 MΩ with a changed force of 1 nN, implying that the pressure sensors have high sensitivity. Stable and repeatable I–V curves through multiple voltage sweepings were accomplished, suggesting that the Si3N4 nanobelts pressure sensors are quite reliable. [ABSTRACT FROM AUTHOR]

Field emission with a low turn-on field and high stability is very important and highly desired for the practical application of nanostructures in electron emitters. In the present study, we report the growth of p-type 3C-SiC nanowires with B dopants and sharp corners created via the catalyst-assisted pyrolysis of a polymeric precursor. The morphologies, structures and field emission (FE) properties of the resultant SiC nanowires were investigated. FE measurements suggest that the B-doped SiC nanowires have excellent FE performance with a low turn-on field of 1.35 V μm−1 and a high field enhancement factor of ∼4895. More importantly, the current emission fluctuation of B-doped nanowires with an applied field of 1.88 V μm−1 at 200 °C could be improved to ∼11% from ∼22% of the undoped counterparts, suggesting that the high-temperature FE stability of SiC nanowires could be significantly enhanced by the B dopants. The excellent FE performances could be attributed to the special p-type triangular prism-like nanostructures with B dopants and numerous sharp corners on the prism edges, which could reduce the effective work function and remarkably increase the emission site density. [ABSTRACT FROM AUTHOR]