RESUMO
The combination of sensing invisible ultraviolet photons and infrared radiation can significantly enhance target recognition by offsetting their own limit in a short sensing range and poor spatial resolution. However, the difference in their wavelength sets unique requirements for sensing materials and devices, which makes it hard to establish their implementation in a single detector. In this work, we present the design of a single detector with CH3NH3PbCl3 (MAPbCl3) for distinguishing ultraviolet and IR signals by switching its operating mode in the photo-/thermo-electric effect. The large optical band gap of â¼3.2 eV in MAPbCl3 ensures the response toward an ultraviolet photon, while its efficient thermoelectric effect allows the sensing of an IR signal. As a result, the detector exhibits a specific detectivity of 4.5 × 1012 Jones for 395 nm ultraviolet photons under 0 V, while under the working voltage of 2.5 V, it demonstrates a superior temperature coefficient of resistance of -3.7% K-1, a specific detectivity of 4.8 × 108 Jones, and a limit of detection of 0.58 mW/cm2 for 4 µm photons. The functionality of the switching response to ultraviolet or IR photons by working voltage allows background subtraction and enhances the target discrimination in the imaging.
RESUMO
In this work, an efficient and robust hole transport layer (HTL) based on blended poly((9,9-dioctylfluorenyl-2,7-diyl)-alt-(9-(2-ethylhexyl)-carbazole-3,6-diyl)) (PF8Cz) and crosslinkable 3,3'-(9,9-dimethyl-9H-fluorene-2,7-diyl)bis(9-(4-vinylphenyl)-9H-carbazole) (FLCZ-V) is introduced for high-performance and stable blue quantum dot-based light-emitting diodes (QLEDs), wherein FLCZ-V can in situ-crosslink to a continuous network polymer after thermal treatment and the linear polymer PF8CZ becomes intertwined and imprisoned. As a result, the blended HTL shows a high hole mobility (1.27 × 10-4 cm2 V-1 s-1) and gradient HOMO levels (-5.4 eV of PF8CZ and -5.7 eV of FLCZ-V) that can facilitate hole injecting so as to ameliorate the charge balance and, at the same time, achieve better electron-blocking capability that can effectively attenuate HTL decomposition. Meanwhile, the crosslinked blended HTL showed excellent solvent resistance and a high surface energy of 40.34 mN/m, which is favorable to enhance wettability for the deposition of a follow-up layer and attain better interfacial contact. Based on the blended HTL, blue QLEDs were fabricated by both spin-coating and inkjet printing. For the spin-coated blue QLED, a remarkable enhancement of external quantum efficiency (EQE) of 15.5% was achieved. Also, the EQE of the inkjet-printed blue QLED reached 9.2%, which is thus far the best result for the inkjet-printed blue QLED.
RESUMO
Sensitive thermometry or thermography by responding to blackbody radiation is urgently desired in the intelligent information life, including scientific research, medical diagnosis, remote sensing, defense, etc. Even though thermography techniques based on infrared sensing have undergone unprecedented development, the poor compatibility with common optical components and the high diffraction limit impose an impediment to their integration into the established photonic integrated circuit or the realization of high-spatial-resolution and high-thermal-resolution imaging. In this work, we present a sensitive temperature-dependent visible photon detection in Bi-doped MAPbX3 (X = Cl, Br, and I) and employ it for uncooled thermography. Systematic measurements reveal that the Bi dopant introduces trap states in MAPbX3, thermal energy facilitates the carriers jumping from trap states to the conduction band, while the vacancies of trap states ensure the sequential absorption of visible photons with energy less than the band gap. Subsequently, the change of response toward the visible photon is applied to construct the thermograph, and it possesses a specific sensitivity of 2.11% K-1 along temperature variation. As a result, our thermograph presents a temperature resolution of 0.21 nA K-1, a high responsivity of 2.06 mA W-1, and a high detectivity of 2.08 × 109 Jones at room temperature. Furthermore, remote thermal imaging is successfully achieved with our thermograph.
RESUMO
A simple and cost-effective material composed of polyacrylonitrile nanofibers containing different concentrations of moringa (MR) leaf extracts was fabricated for antimicrobial properties and wound dressing. The fabricated materials were characterized by scanning electron microscopy, thermal gravimetric analysis, and Fourier transmission infrared spectroscopy. The antibacterial sensitivity of the developed polyacrylonitrile-moringa extract nanofibers was evaluated against Staphylococcus aureus and Escherichia coli by the agar diffusion method. A pronounced antibacterial activity was observed with the increase in the incorporated moringa leaf extract concentration within the polyacrylonitrile-moringa extract nanofibers against the bacterial strains. The best antibacterial sensitivity was observed for nanofibers containing 0.5 g of moringa leaf extract which had an inhibitory zone of 15 mm for E. coli and 12 mm for S. aureus. Furthermore, the cost-effective and biodegradable nanofibrous polyacrylonitrile-moringa extract nanofiber was also used to conduct further studies regarding wound dressing. The result reveals that the increase in the concentrations of moringa leaf extract influenced the healing properties of the material. For days 1, 4, and 7 of the wound dressing experiment, the % wound closure of the rat was the highest for the nanofiber containing 0.5 g of moringa leaf extract (35, 87, and 95%, respectively) compared to the positive control medical gauze (29, 75, and 93%, respectively).