Design of Extended Channel Ge-source TFET for Low Power Applications

In this paper, a novel design of a TFET structure using Ge-source and extending a part of the channel into the source is proposed. The DC performance is analyzed by evaluating the ON current, ION/IOFF ratio and subthreshold swing (SS). Moreover, the high-frequency performance is inspected in terms of transconductance (gm) and unit-gain cutoff frequency (fT). All simulations are performed utilizing 2D SILVACO TCAD. It is demonstrated that the ON current and the cut-off frequency can be simultaneously improved by appropriate design of the proposed structure

An Autonomous Wearable Sensor Node for Long-Term Healthcare Monitoring Powered by a Photovoltaic Energy Harvesting System

oai:ojs.ijet.ise.pw.edu.pl:article/2503In this paper, an autonomous wearable sensor node is developed for long-term continuous healthcare monitoring. This node is used to monitor the body temperature and heart rate of a human through a mobile application. Thus, it includes a temperature sensor, a heart pulse sensor, a low-power microcontroller, and a Bluetooth low energy (BLE) module. The power supply of the node is a lithium-ion rechargeable battery, but this battery has a limited lifetime. Therefore, a photovoltaic (PV) energy harvesting system is proposed to prolong the battery lifetime of the sensor node. The PV energy harvesting system consists of a flexible photovoltaic panel, and a charging controller. This PV energy harvesting system is practically tested outdoor under lighting intensity of 1000 W/m2. Experimentally, the overall power consumption of the node is 4.97 mW and its lifetime about 246 hours in active-sleep mode. Finally, the experimental results demonstrate long-term and sustainable operation for the wearable sensor node

Design of Extended Channel Ge-source TFET for Low Power Applications

In this paper, a novel design of a TFET structure using Ge-source and extending a part of the channel into the source is proposed. The DC performance is analyzed by evaluating the ON current, ION/IOFF ratio and subthreshold swing (SS). Moreover, the high-frequency performance is inspected in terms of transconductance (gm) and unit-gain cutoff frequency (fT). All simulations are performed utilizing 2D SILVACO TCAD. It is demonstrated that the ON current and the cut-off frequency can be simultaneously improved by appropriate design of the proposed structure

Experimental and numerical investigations of the corona characteristics of a new Tri-electrode system for electrostatic separation processes

The paper presents the measurement and computation of the corona onset voltages, electric field and ion current density profiles of a new “Tri-electrode system” intended for electrostatic separation applications. Unlike the well-known “dual cylinder-wire electrode system”, the new system utilizes an extra adjustable wire in order to provide the means for a more efficient ion charging current; necessary for separation of different granular mixtures. An experimental setup is constructed to model the present multi-electrode arrangement. The measurements are carried out for wire diameters between 0.3–1.0 μm and for different geometrical parameters. Without resorting to the commonly used Deutch’s assumption, a computational scheme is developed to solve the corona equations and to compute the associated ionized field quantities of the system. Mapping of the ion flow field patterns demonstrates the impact of this assumption on the solution’s accuracy. The computed results were found to be in good agreement with experiments. The configuration offers a more efficient charging process and separation in comparison with earlier separators’ designs

An equivalent electrode system for efficient charging of filtration media

This paper concerns the influence of moving an auxiliary limiting cylinder in X-Y directions on the electrostatic field and corona onset voltage of the dual electrode system employed in the electrostatic filtration process resulting in a “Tri-electrode” system. The Tri-electrode system is applied in order to control the field around the ionized wire and on the ground plate. Accurate calculation of the electrostatic field is obtained using the charge simulation method coupled with genetic algorithms. The calculated field values are utilized in computing the corona onset voltage of the ionized electrode. Laboratory measurements of the onset voltage of the ionized electrode are applied. It is found that the limiting cylinder controls the onset voltage of the ionized wire such that the ionized wire may be in ionized or non-ionized state without changing the position of the ionized wire itself. The numerical onset voltage values agreed satisfactorily with those measured experimentally. Keywords: Corona discharge, Tri-electrode system, Filtration media, Electric fiel

Experimental and numerical investigations of the Laplacian and Poissonian field in asymmetric multiple-electrode systems for electrostatic separation processes

The paper presents an experimental measurements and numerical computations of the electric field in Laplacian field model as well as Poissonian field model for various asymmetric multiple-electrode configurations prepared to electrostatic separation processes. The asymmetric multiple-electrode systems utilize additional cylindrical rods and/or L-plates connected at constant or floating potential, as in practical applications. The geometries include a cluster of spherical/cylindrical conducting particles uniformly distributed and simultaneously in contact with the ground plate. The charge simulation method integrated with genetic algorithm and method of characteristics is employed for numerical computation and analysis of the electric field in the presented models. Neglecting Deutch’s assumption, the numerical technique is applied to solve Laplace's equation or Poisson's equation with the current-continuity relation. Influence of the cluster of spherical/cylindrical particles on the electric field distribution on the ground plate surface, and its acquired charged, is established. I-V characteristics and the spatial distributions of current density and electric field are evaluated and assessed. The experimental results were found to be in a good agreement with analytical values. Keywords: Electric field, Corona discharge, Electrostatic separation application

Investigation of Electron Transport Material-Free Perovskite/CIGS Tandem Solar Cell

Tandem solar cells have a superb potential to push the power conversion efficiency (PCE) of photovoltaic technologies. They can be also more stable and economical. In this simulation work, an efficient perovskite solar cell (PSC) with Spiro-OMeTAD as a hole transport material (HTM) and with no electron transport material (ETM) to replace the traditional PSC structure is presented. This PSC is then used as a top sub cell together with a copper indium gallium sulfide (CIGS) bottom sub cell to build a tandem cell. The multi-junction solar cell behavior is improved by engineering the technological and physical parameters of the perovskite and HTM. The results show that an n-p heterojunction PSC structure with an ETM free could be a good candidate for the traditional n-i-p structure. Because of such investigations, the performance of the proposed ETM-free PSC/CIGS cell could be designed to reach a PCE as high as 35.36%

Full Optoelectronic Simulation of Lead-Free Perovskite/Organic Tandem Solar Cells

Organic and perovskite semiconductor materials are considered an interesting combination thanks to their similar processing technologies and band gap tunability. Here, we present the design and analysis of perovskite/organic tandem solar cells (TSCs) by using a full optoelectronic simulator (SETFOS). A wide band gap lead-free ASnI2Br perovskite top subcell is utilized in conjunction with a narrow band gap DPPEZnP-TBO:PC61BM heterojunction organic bottom subcell to form the tandem configuration. The top and bottom cells were designed according to previous experimental work keeping the same materials and physical parameters. The calibration of the two cells regarding simulation and experimental data shows very good agreement, implying the validation of the simulation process. Accordingly, the two cells are combined to develop a 2T tandem cell. Further, upon optimizing the thickness of the front and rear subcells, a current matching condition is satisfied for which the proposed perovskite/organic TSC achieves an efficiency of 13.32%, Jsc of 13.74 mA/cm2, and Voc of 1.486 V. On the other hand, when optimizing the tandem by utilizing full optoelectronic simulation, the tandem shows a higher efficiency of about 14%, although it achieves a decreased Jsc of 12.27 mA/cm2. The study shows that the efficiency can be further improved when concurrently optimizing the various tandem layers by global optimization routines. Furthermore, the impact of defects is demonstrated to highlight other possible routes to improve efficiency. The current simulation study can provide a physical understanding and potential directions for further efficiency improvement for lead-free perovskite/organic TSC