Ultraviolet light

About: Ultraviolet light is a research topic. Over the lifetime, 49494 publications have been published within this topic receiving 843151 citations.

High-speed colour-converting photodetector with all-inorganic CsPbBr3 perovskite nanocrystals for ultraviolet light communication

Abstract: Optical wireless communication (OWC) using the ultra-broad spectrum of the visible-to-ultraviolet (UV) wavelength region remains a vital field of research for mitigating the saturated bandwidth of radio-frequency (RF) communication. However, the lack of an efficient UV photodetection methodology hinders the development of UV-based communication. The key technological impediment is related to the low UV-photon absorption in existing silicon photodetectors, which offer low-cost and mature platforms. To address this technology gap, we report a hybrid Si-based photodetection scheme by incorporating CsPbBr3 perovskite nanocrystals (NCs) with a high photoluminescence quantum yield (PLQY) and a fast photoluminescence (PL) decay time as a UV-to-visible colour-converting layer for high-speed solar-blind UV communication. The facile formation of drop-cast CsPbBr3 perovskite NCs leads to a high PLQY of up to ~73% and strong absorption in the UV region. With the addition of the NC layer, a nearly threefold improvement in the responsivity and an increase of ~25% in the external quantum efficiency (EQE) of the solar-blind region compared to a commercial silicon-based photodetector were observed. Moreover, time-resolved photoluminescence measurements demonstrated a decay time of 4.5 ns under a 372-nm UV excitation source, thus elucidating the potential of this layer as a fast colour-converting layer. A high data rate of up to 34 Mbps in solar-blind communication was achieved using the hybrid CsPbBr3–silicon photodetection scheme in conjunction with a 278-nm UVC light-emitting diode (LED). These findings demonstrate the feasibility of an integrated high-speed photoreceiver design of a composition-tuneable perovskite-based phosphor and a low-cost silicon-based photodetector for UV communication. A silicon-based receiver that incorporates perovskite nanocrystals efficiently detects ultraviolet signals, paving the way towards high-speed, high-bandwidth UV wireless communication. The photodetector (PD), developed by Boon S. Ooi of King Abdullah University of Science and Technology (KAUST) and colleagues in Saudi Arabia, is less bulky and cheaper to manufacture than currently available receivers. It builds on technologically advanced silicon-based PDs, which are compact and widely available, but respond best to higher wavelength green light. Incorporating cesium lead bromide (CsPbBr3) perovskite nanocrystals into a silicon-based PD facilitated efficient conversion of UV into green light. The team demonstrated that their receiver could be used in high-speed UV-based communication, paving the way for the use of perovskite-based materials in terrestrial and underwater UV-Internet systems.

An Efficient Way to Assemble ZnS Nanobelts as Ultraviolet-Light Sensors with Enhanced Photocurrent and Stability

Abstract: Although there has been significant progress in the fabrication and performance optimization of one-dimensional nanostructure-based photodetectors, it is still a challenge to develop an effective and low-cost device with high performance characteristics, such as a high photocurrent/ dark-current ratio, photocurrent stability, and fast time response. Herein an efficient and low-cost method to achieve high-performance 'visible-blind' microscale ZnS nanobelt-based ultraviolet (UV)-light sensors without using a lithography technique, by increasing the nanobelt surface areas exposed to light, is reported. The devices exhibit about 750 times enhancement of a photocurrent compared with individual nanobelt-based sensors and an ultrafast time response. The photocurrent stability and time response to UV-light do not change significantly when a channel distance is altered from 2 to 100 μm or the sensor environment changes from air to vacuum and different measurement temperatures (60 and 150°C). The photoelectrical behaviors can be recovered well after returning the measurement conditions to air and room temperature again. The low cost and high performance of the resultant ZnS nanobelt photodetectors guarantee their highest potential for visible-blind UV-light sensors working in the UV-A band.

Ultraviolet Light in Food Technology: Principles and Applications

Abstract: Principles and Applications of UV Technology Basic Principles of UV Light Technology Propagation of UV Light Application Guidance in Food Processing Current Status of US and International Regulations Sources of UV Light Introduction Mercury-Emission Lamps Amalgam UV Lamps Special Lamp Technologies Guidelines for Choice of Lamp Technology Characterization of Foods in Relation to UV Treatment Terms and Definitions Analytical Measurements Absorptive and Physicochemical Properties of Liquid Foods Food Solids and Surfaces Conclusions Microbial Inactivation by UV Light Mechanisms of Microbial Inactivation by UV Light UV Sensitivity of Pathogenic and Spoilage Food-Borne Microorganisms UV Sensitivity of Waterborne Pathogens UV Sensitivity of Food-Borne Pathogens UV Inactivation Kinetics and Competitive Effects in Foods: Absorbance, pH, Solids, and Other Components Methods to Measure, Quantify, and Mathematically Model UV Inactivation Efficacy of Low-Pressure, High-Intensity Lamp for Inactivation of Food Pathogen Conclusions UV Processing Effects on Quality of Foods Basic Considerations Chemistry of the Photodegradation of Organic Compounds Shelf Life and Quality Changes in Fresh Juices Effects of UV Light on Degradation of Essential Vitamins Effect of UV Processing on Milk Quality Shelf Life and Quality Changes in Fresh Produce Degradation and Formation of Chemical Compounds in Foods Conclusions Transport Phenomena in UV Processing UV Irradiance in Liquid Foods General Hydraulic Condition UV Process Calculations for Food Applications Establishment of Specifications for Preservation Delivery of the Scheduled Process Measurement of UV Dose Delivery Conclusions Reactor Designs for the UV Treatment of Liquid Foods Laminar Flow in Concentric Cylinders Turbulent Flow in Concentric Cylinders Taylor-Couette Flow in Concentric Cylinders Comparison of Disinfection in Concentric Cylinders Turbulent Channel Flow Dean Flow Reactor Evaluation of UV Reactor Design UDF Source C Codes Principles of Validation of UV Light Pasteurization Validation Concept Validation at Different Phases of Process Development-Scale-Up Process Key Components of Validation Procedures Conclusions Pulsed-Light Treatment: Principles and Applications Description of Pulsed-Light Treatment Inactivation of Microorganisms by Pulsed-Light Treatment Applications of Pulsed-Light Treatment Future Prospects of Pulsed-Light Treatment in the Food Industry References appear at the end of each chapter.