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Micro-spherical Na3V2(PO4)2F3@C/CNTs with a high tap density of 1.2 g cm−3have been developed and display excellent performances for sodium-ion batteries.

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Lead halide perovskites are widely used for optoelectronic devices because they possess a high charge carrier mobility, high photoconversion efficiency, low energy cost, etc. However, lead toxicity and instability of these perovskites prevent their wide-scale industrial applications. Herein, we successfully fabricated the lead-free Ce 3+ doped Cs 3 MnBr 5 metal halide nanocrystals (MHNCs), which displays a broad UV response and an efficient blue photoluminescence at 398 and 423 nm. The introduction of Ce 3+ ions results in a broadband response to UV light, a highly improved photoluminescence quantum yield from 38% to 90%, and an improved longtime stability. The highly desirable broadband UV photodetector was fabricated based on the Ce 3+ doped Cs 3 MnBr 5 MHNCs film, which shows a broadband response to UV light ranging from 200 to 380 nm. The responsivity was 1.1 A/W with a millisecond rise/fall time response. This study demonstrates a strategy of fabricating the broadband UV photodetector for novel and advanced UV optoelectronic systems.

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Broadband photodetection (PD) covering the deep ultraviolet to near-infrared (200–1000 nm) range is significant and desirable for various optoelectronic designs. Herein, we employ ultraviolet (UV) luminescent concentrators (LC), iodine-based perovskite quantum dots (PQDs), and organic bulk heterojunction (BHJ) as the UV, visible, and near-infrared (NIR) photosensitive layers, respectively, to construct a broadband heterojunction PD. Firstly, experimental and theoretical results reveal that optoelectronic properties and stability of CsPbI3 PQDs are significantly improved through Er3+ doping, owing to the reduced defect density, improved charge mobility, increased formation energy, tolerance factor, etc. The narrow bandgap of CsPbI3:Er3+ PQDs serves as a visible photosensitive layer of PD. Secondly, considering the matchable energy bandgap, the BHJ (BTP-4Cl: PBDB-TF) is selected as to NIR absorption layer to fabricate the hybrid structure with CsPbI3:Er3+ PQDs. Thirdly, UV LC converts the UV light (200–400 nm) to visible light (400–700 nm), which is further absorbed by CsPbI3:Er3+ PQDs. In contrast with other perovskites PDs and commercial Si PDs, our PD presents a relatively wide response range and high detectivity especially in UV and NIR regions (two orders of magnitude increase that of commercial Si PDs). Furthermore, the PD also demonstrates significantly enhanced air- and UV- stability, and the photocurrent of the device maintains 81.5% of the original one after 5000 cycles. This work highlights a new attempt for designing broadband PDs, which has application potential in optoelectronic devices.

Solid composite polymer electrolytes are the optimal candidate for all solid-state lithium batteries, because of their enhanced ionic conductivities, long-life cycle ability and compatibility to lithium anode. Herein, we reported a kind of solid composite polymer electrolyte comprised of poly(ethylene oxide), graphitic-like carbon nitride and lithium perchlorate, which was prepared by a facile solution blending method. Microstructure of the solid composite polymer electrolyte was regulated by thermal annealing and interaction among components and was characterized by XRD, DSC, FTIR-ATR, and ROM. The obtained solid composite polymer electrolyte achieved an ionic conductivity as high as 1.76 × 10 −5 S cm −1 at 25°C. And the electrochemical stable window and the lithium ion transference number, t + , were also obviously enhanced. LiFePO 4 /Li solid-state batteries with the annealed PEO-LiClO 4 -g-C 3 N 4 solid polymer electrolyte presented a high initial discharge capacity of 161.2 mAh g −1 and superior cycle stability with a capacity retention ratio of 81% after 200 cycles at 1C at 80°C. The above results indicates that the thermal annealing treatment and g-C 3 N 4 as a novel structure modifier is crucial for obtaining the high-performance solid composite polymer electrolytes used in the all solid-state lithium battery.

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