Hengjuan Deng,Xinxin Han,Juan Wang,Dongxi Liu,Bingsuo Zou
Near-infrared (NIR) light source technology has been integrated into mobile devices with the advantage of portability to provide efficient analysis in many fields. Among them, NIR light in the 850 nm band has attracted much attention due to its unique advantages. In this study, an ultra-broad NIR emission from 700 to 1100 nm with the peak at 839 nm and full width at half-maximum (FWHM) of 151 nm is achieved in a novel tetra-fluoride RbAlF4:Cr 3+ excited by 465 nm blue light, exhibiting a relatively longer emission wavelength and wider FWHM compared with the reported Cr 3+ -doped fluoride phosphors. In-depth research on its crystal structure reveals that Cr 3+ is in a weak crystal field with a distorted octahedral environment, coupled with a strong electron-phonon coupling effect, which prompts the phosphor to exhibit long-wavelength and broad NIR light characteristics. However, these reasons also lead to relatively moderate internal quantum efficiency and thermal stability. Finally, a NIR phosphor-converted light-emitting diode (NIR pc-LED) was fabricated by combining this phosphor with a commercial blue chip, which shows great potential in non-destructive testing, night-vision observation, and biomedical imaging. This work provides new insights into the design of long-wavelength broadband fluoride phosphors.
Yuquan Chen,Perumal Veeramalai Chandrasekar,Chuanbo Li,Sree Pammi,Jagadeesh Babu Bellam,Xiaoming Zhang,Peipei Ma
Broad band photodetectors are found to be the inevitable component both in scientific and industrial field. Here, PbSe colloidal QDs prepared by a simple, inexpensive hot injection method were used to fabricate ultra broadband photodetectors with visible to near-infrared sensing capabilities. The as-fabricated photodetector has a wide spectral response and a stable photoelectric response to lasers with wavelengths ranging from 405 nm to 1550 nm. The photovoltaic detector responsivity is 1.43 mA/W at 405 nm, 4.67 mA/W at 980 nm and 0.2 mA/W at1550 nm. The device with optimized structure provides the maximum Voc of 250 mV under 780 nm light illumination and 100 mV even under 1550 nm illumination. Specifically, the detectivity value reaches up to 4.54×109 Jones at 1550 nm laser illumination with intensity of 0.41 mW/cm2. As a result, the current study's findings serve as the foundation for the creation of a broad band photodetector that can detect light from visible to near infrared spectrum.
Xingyu Xu,Weilong Zhang,Yan Hu,Yuanhao Wang,Lin Lu,Shujun Wang
Solar heat blocking materials, which can not only strongly shield the near infrared (NIR) heat rays, but also retain high visible transparency, have been widely studied and used in energy conservation of buildings . In this work, a complete process for preparation of waveband two-component transparent NIR shielding (WTNS) coatings combined ATO (antimony doped tin oxide) and Cs 0.33 WO 3 nanomaterials is proposed. ATO and Cs 0.33 WO 3 were synthesized by controllable hydrothermal methods and dispersed by a ball mill with silane coupling agents . The transmittance spectra demonstrate that WTNS coated glass shows excellent NIR shielding performance in a wide-band wavelength from 780 nm to 2500 nm, which could shield the NIR light as much as 90.9% and retain high transparency in the visible light of 70.6%. The overall energy performance assessment of this NIR shielding coatings was obtained, which includes thermal chamber test and software simulation in EnergyPlus . The chamber tests reveal the superior thermal insulation ability of WTNS coatings. The simulations indicate that for the area like Hong Kong which is cooling dominated areas, WTNS coated glass has the best energy performance which can significantly save up to 15.22% and 9.15% electricity per year in comparison with the normal glass and low-e glass, respectively.
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