Search

The perovskite single crystals (PSC) produced by solution‐processed metallic ions doping have a thick p–n junction (greater than 10 µm). Meanwhile, to achieve high responsivity, the carrier drift length (µτE) has to be larger than the dimensions of the detector. If the p–n junction is quite thick, a high bias voltage is required. For the practical application of photodiode, it is imperative to find a means to generate a thin p–n junction. A productive technique is suggested for forming a thin p–n junction by diffusing metallic ions, resulting in a longer drift length of the carrier than the depletion width. Thinner p–n junction leads to reduced dark current density (0.5 µA cm−2), low trap density (5.71 × 108 cm−3), high mobility (417 cm2 V−1 s−1), and hence increased responsivity (77.69 A W−1) for 30 µW cm−2 UV illumination under a low applied voltage of −15 V. A quick response time with a rise/fall duration of 22 ms/30 ms under 0 V and long‐term stability for over 3 months in ambient airis achieved. To comprehend the performance with the thinner p–n junction‐based photodiodes, the results under UV–Vis illumination are examined and compared. The outcomes hint at a method that holds promise for producing efficient photodiodes. [ABSTRACT FROM AUTHOR]

Mechanical energy harvesters fabricated with halide perovskites display excellent electrical output because of their prominent permittivity. An all-inorganic lead-free double perovskite, Cs2AgBiBr6 (CABB), with competitive performance, excellent environmental stability and non-toxicity can break the confines of practical unavailability. CABB microcrystals, which are effective nucleating agents and dielectric fillers, are embedded into a polyvinylidene-fluoride (PVDF)-matrix as efficient electron-acceptors to induce electro-active PVDF β-phase formation and enhance the composite dielectric constant, which contributes to notable hybrid electric outputs. CABB–PVDF hybrid nanogenerators with the optimal CABB concentration of 20 wt% possess triboelectric and piezoelectric effects, with a nanogenerator with a 1.2 cm × 1.2 cm effective contact area and 70 μm film thickness exhibiting a unique response with an open-circuit voltage of 126 V and a short-current density of 4.67 mA m−2 under a 0.5 Hz mechanical frequency and 4 cm s−1 motion speed. An identical device achieves the highest output power density of 0.39 W m−2 at 8 Hz and 0.64 m s−1, which could light up at least 86 commercial LEDs using a 1 μF capacitor and power small electronic devices such as a timer using 22 μF. The corresponding force sensing is achieved with a different distribution of external forces using a 10 wt% CABB–PVDF composite film. This functional composite maintains its stability and charge retention capacity for effective application in various environmental conditions. [ABSTRACT FROM AUTHOR]

This study presents an error flow research method for simulation models of hydraulic systems in construction machinery based on the state-space approach, aiming to ensure the reliable application of digital twin models. Initially, a comprehensive analysis of errors in the simulation modeling of hydraulic systems in construction machinery was conducted, highlighting simulation model parameters as the primary error sources. Subsequently, a set of metrics for assessing the accuracy of simulation models was developed. Following this, an error flow analysis method for simulation models of hydraulic systems in construction machinery was explored based on the state space approach, delving into the sources, transmission, and accumulation of errors in the simulation modeling of valve-controlled cylinder systems. The research results unequivocally indicate that the spring stiffness, viscous damping coefficient, and hydraulic cylinder external leakage coefficient are critical parameters affecting the accuracy of valve-controlled cylinder system simulation models. Furthermore, it was observed that the simulation model of the control valve has a significantly greater impact on the errors in the valve-controlled cylinder system simulation model than the hydraulic cylinder model. In conclusion, the reliability of the error flow model was confirmed through simulation experiments, revealing a maximum relative error of only 3.73% between the error flow model and the results of the simulation experiments. [ABSTRACT FROM AUTHOR]

Perovskite single crystals (PSCs) photodiodes with p–n junctions have been widely studied due to their effective blocking of injected current with barriers and quickly separating the electrons and hole pairs with a built-in electric field. Here, we report a solution-processed epitaxial (SPE) growth method to fabricate p–n photodiodes based on MAPbBr3 PSCs. In the structure of the MAPbBr3 PSCs, bismuth donor doping will change the conduction type from p-type to n-type and redshift the absorption edge along with the increase in Bi concentration. Therefore, this work successfully fabricates the p–n photodiodes with homo-epitaxial Bi-doped (n-type) MAPbBr3 layers grown on the surface of undoped (p-type) MAPbBr3 PSCs substrates through the SPE growth method. The p–n photodiodes achieve a tunable spectral response by simply adjusting the Bi doping concentrations of homo-epitaxial MAPbBr3 layers. The spectral response peaks redshift from 559 to 601 nm, with an increasing Bi doping level of 0% to 15%. [ABSTRACT FROM AUTHOR]

Low‐cost and efficient large‐scale triboelectric nanogenerator (TENG) is considered as the new scheme for distributed mechanical conversion or renewable energy utilization. An extremely popular all‐inorganic lead‐free double perovskite Cs2AgBiBr6 (CABB) has emerged as extraordinary potential material in triboelectric semiconductors' substitution, overcoming high‐impedance limitations associated with organic‐polymer‐insulator based materials. In this study, assembled by the certified available positive frictional material CABB, TENG with sandwiched structure of ITO/compact‐TiO2/mesoporous‐TiO2/CABB – the poly‐tetra‐fluoroethylene/Al exhibits appropriate performance on environmental stability and output capacity for which structure can impede charges decay. Fabrication process comparison shows that as an inexpensive large‐scale functional films preparation method, sprayed CABB TENG with brilliant relative dielectric constant and work function difference possess more distinguished output characteristics. This is confirmed by higher open‐circuit voltage of 105 V, larger short‐current density of 2.45 mA m−2 at 0.25 Hz motion parameter, and more abundant output power density of 0.76 W m−2 under 10 Hz. Further study confirms that both higher frequency and larger contact‐area are conducive to total output power, while terminal charging speed is inversely or positively proportional with capacitance or mechanical frequency. Final physical display effect of sprayed CABB TENG lights up at least 53 commercial yellow‐LEDs, holding decent energy conversion ability. [ABSTRACT FROM AUTHOR]

Single-crystalline perovskites with low trap density, high mobility, and long diffusion length are ideal for creating high-performance optoelectronic devices. However, growing mixed-halide single-crystalline perovskite films or wafers with arbitrary halide components and controlled thickness is challenging. Here, a liquid-phase epitaxial (LPE) method based on inverse temperature crystallization (ITC) was developed to address this issue, using orientated MAPbCl3 single crystals as substrates, resulting in a series of single-crystalline MAPbBrxCl3−x perovskite films with continuous variable bandgaps from 2.19 eV to 2.91 eV and excellent optical-electrical properties. A series of planar-type photodetectors are designed and fabricated based on the epitaxial single-crystalline MAPbBrxCl3−x films, which present a dual-mode detection ability with response in both broadband and narrowband spectra ranges by manipulating the light incident direction from top illumination and bottom illumination, respectively. Through adjusting halide compositions, these photodetectors exhibit a selective optimal response spectrum and excellent optoelectronic detection performance, demonstrating the potential for multi-functional spectral detection with epitaxial perovskite devices. [ABSTRACT FROM AUTHOR]

Narrowband photodetection provides important information in a specific wavelength range. Specially, the use of nonoptical‐filter narrowband photodetectors based on MAPbX3 (MA = CH3NH3; X = Cl, Br, I) perovskites is reported of great potential. However, current MAPbX3‐based narrowband photodetectors have to sacrifice their photocurrent and response speed to achieve an acceptable spectral rejection ratio. In this work, a new type of heterojunction photodetector (hetero‐PD) with a structure of (n‐type doped MAPbCl3)/(intrinsic MAPbBr2.5Cl0.5)/(n‐type doped MAPbBr3) via epitaxial growth is demonstrated as a narrowband photodetector. Through optical bandgap engineering, photons with different wavelength can be absorbed in different layers. Owing to the n–i–n energy band structure, most external bias would apply on a tiny region near the n–i heterojunction. Besides, the energy barriers in the heterojunctions can block holes from injection and collection, resulting in low‐noise electron‐only hetero‐PDs. By sufficiently suppressing the background noise from short‐wavelength photons, hetero‐PDs are capable of achieving a high spectral rejection ratio of 98.1% under an electrical field of 8 V cm−1. Moreover, hetero‐PDs exhibit a high external quantum efficiency value of 45%, a narrow full width at half‐maximum of 13 nm, and a response time of 1.35 µs. [ABSTRACT FROM AUTHOR]