The bandgap and type of optical transition are key factors in determining the functionalities and applications of photoelectric materials. However, it is extremely difficult to modulate the bandgap and indirect‐direct bandgap transition for most materials. This study reports significant enhancements in photocurrents and an extended detection bandwidth resulting from pressure‐regulated indirect–direct bandgap transition in hypervalent CsI3. Furthermore, this study achieves an increase in the photocurrent by almost five orders of magnitude under visible‐light illumination. Impressively, the detection band‐edge shows a successive redshift from visible light to 1650 nm (optical communication waveband) upon compression. And high pressure is conducive to CsI3 operating at an ultralow bias input. Extensive high‐pressure spectroscopy analyses and theoretical calculations suggest that changes in the photoelectric properties of CsI3 are associated with enhanced I–I interactions along the quasi‐endless linear chain directions under compression. These findings offer an effective band engineering strategy for achieving broadband spectral response and high gains with an ultralow bias in photoelectric detectors.
Achieving high-efficiency solid state emission is essential for practical applications of organic luminescent materials. However, intermolecular interactions generally induce formation of multimeric aggregate excited states with deficient emissive ability, making it extremely challenging to enhance emission in aggregated states. Here we demonstrate a novel strategy of continuously regulating multimeric excitation constituents with a high-pressure technique successfully enhancing the emission in a representative organic charge-transfer material, Laurdan (6-lauroyl-N,Ndimethyl-2-naphthylamine). The Laurdan crystal exhibits distinct emission enhancement up to 4.1 GPa accompanied by a shift in the emission color from blue to cyan. Under compression, the π−π interplanar distance in Laurdan multimers is reduced, and intermolecular wave function diffusion is demonstrated to be improved simultaneously, which results in local excitation promotion and thus enhanced emission. Our findings not only provide new insights into multimeric excited state emission modulation but also pave the way for the further design of high-performance aggregated luminophores.
This paper describes a low cost and efficient electromagnetic vibration energy harvester (EVEH) for a self-powered system. The EVEH consists of a resistant (copper) spring, a permanent magnet (NdFeB35) and a wire-wound copper coil. The copper spring was fabricated by the laser precision cutting technology. A numerical model was adopted to analyze magnetic field distribution of a rectangle permanent magnet. The finite element (FEM) soft ANSYS was used to simulate the mechanical properties of the system. The testing results show that the micro electromagnetic vibration energy harvester can generate the maximal power 205.38 μW at a resonance frequency of 124.2 Hz with an acceleration of 0.5 g (g = 9.8 ms−2) across a load the 265 Ω and a superior normalized power density (NPD) of 456.5 μW cm−3 g−2. The magnetic field distribution of the permanent magnet was calculated to optimize geometric parameters of the coil. The proposed EVEH has a high efficiency with the lower cost.
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