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(p×n)-type transverse thermoelectrics were proposed as a potential superior thermoelectric material for Peltier cooling at cryogenic temperature and integrated thermoelectric devices. In transverse thermoelectric materials, highly anisotropic ambipolar conduction leads to the opportunity to achieve off-diagonal Seebeck coefficient through proper orientation, which generates a voltage drop perpendicular to the temperature gradient. Some anisotropic thermoelectric materials are found to have ambipolar Seebeck effect, with a negative Seebeck coefficient along one direction and positive orthogonal Seebeck, hence the name (p×n)-type. However, such experiments only measured Seebeck coefficients along particular crystal axes, which is insufficient to map the full Seebeck tensor. Also, different samples are often used for different orientations so sample inhomogeneity makes such measurements less reliable. Here, we report results for an all-in-one measurement set-up for measuring the full Seebeck tensor on a single sample with custom-made apparatus. The details of the fabrication, sources of error, and typical measurements are described. Measurements on pre-characterized isotropic thermoelectric material PbTe are reported. The obtained diagonal Seebeck coefficients agree with results from standard measurement methods to within 10%, and the errors introduced in the 6 off-diagonal terms are less than 5% of the diagonal values. Anisotropic van der Pauw measurements can also be integrated into the apparatus to measure the full anisotropic resistivity tensor on the same sample.

AIP Publishing Horizons - Energy Storage and Conversion

Full Experimental Seebeck Tensor Characterization for (p × n)-Type Transverse Thermoelectrics

seebeck

thermoelectric

anisotropy


![](https://assets.underline.io/uploads/markdown_image/1/image/2e10c515564e9ec3287ee4c664011c20.png)

The energy cost of storing and moving data is enormous, and is growing at such a rapid pace that within a few years the power demand may overwhelm some developed nations. Non-volatile memory (NVM) and neuromorphic computing are enabling critical advances in this area, but there are many scientific and technological challenges. This conference will cover the materials challenges of different memory technologies, from the fundamental processes and mechanisms, to industry perspectives on materials specifications and manufacturing.

Materials Challenges for Memory

poster

Energy conversion and storage is a critical part of modern society. Applications continue to develop at a fast pace, from the development of new generation battery materials, to environmental sensors, catalytic materials for sustainable energy and solar cells and photodetectors. This conference will cover the latest advances in energy related fields and debate the needs and priorities currently existing or emerging in this field over the next few decades.

Conference Topics:

* Batteries and supercapacitors
* Catalytic materials and water splitting
* Light emitting materials and devices
* Solar cells and photodetectors
* Thermoelectric materials
* Sensing and environmental monitoring systems


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Energy conversion and storage is a critical part of modern society. Applications continue to develop at a fast pace, from the development of new generation battery materials, to environmental sensors, catalytic materials for sustainable energy and solar cells and photodetectors. This conference will cover the latest advances in energy related fields and debate the needs and priorities currently existing or emerging in this field over the next few decades.

Ocean related activities are often supported by offshore equipment with particular power demands. These are usually deployed at remote locations and have limited space, thus small energy harvesting technologies, such as photovoltaic panels or wind turbines, are used to power their instruments. However, the inherent energy sources are intermittent and have lower density and predictability than an alternative source: wave energy.1 The triboelectric nanogenerator (TENG) is a promising and efficient energy harvesting technology capable of addressing these problems as it can efficiently convert regular/irregular external mechanical energy into electrical power based on the triboelectrification and electrostatic induction effects.2-4 In this work, three TENGs based on rolling-spheres were developed and their performance compared in both a “dry” bench testing system under rotating motions, and in a large-scale wave basin under realistic sea-states installed within a scaled navigation buoy. The experiments showed that the electrical outputs of these TENGs tend to rise with increasing pitch amplitudes and decreasing period due to the increase of the spheres’ velocity. The capability of these TENGs to harvest energy from ocean waves when incorporated into a navigational buoy was demonstrated under realistic sea states. The voltage generated by the TENGs achieves maximum values for periods close to the natural period of the scaled buoy (~ 0.92 s). The wave basin tests clearly demonstrated a significant dependency of the electrical outputs on the pitch degree of freedom and the need to consider the full dynamics of the buoy, and not only that of TENGs, when subjected to the excitations of waves.

Performance of triboelectric nanogenerators based on rolling spheres motion under realistic water waves conditions

A study on the effects of porosity on the capacitance of p-doped Si electrodes was carried out in the presented work. For that two different parameters, namely the porosification time and the current density applied in the anodization process have been varied and as a result 12 types of porous Si electrodes, corresponding to 6 different current densities and 2 different time durations, were obtained and evaluated in a plane parallel capacitor configuration through EIS, CV and C&D measurements. In addition to porosification, the electrodes have also been modified through electrodeposition of a conductive polymer and thermal treatment towards obtaining activated carbon at the surface.

In-depth analysis of porous Si electrodes for supercapacitors

The successful isolation of graphene (in 2004) and phosphorene (atomic layer thick black phosphorus) in 2014 and MXene (year 2011) has currently aroused the interest of 2D material researchers. In this review, first, the fundamentals of graphene and phosphorene and MXene, are briefly introduced, along with their structures, properties, and synthesis methods. Second, the readers are presented with an overview of their energy applications. Particularly in electrochemical energy storage, the large interlayer spacing (0.53 nm) in phosphorene allows the intercalation/deintercalation of larger ions as compared to its graphene counterpart (0.33 nm). Therefore, phosphorene may possess greater potential for high electrochemical performance for sodium ion batteries while graphene hold the promise for lithium ion batteries. Next, each application for energy generation, conversion, and storage is described in detail with milestones as well as the challenges. These emerging applications include supercapacitors, photovoltaic devices, water splitting, photocatalytic hydrogenation, oxygen evolution, and thermoelectric generators. Finally the fast-growing dynamic field of 2D research is summarized and perspectives on future possibilities are presented calling on the efforts of chemists, physicists, and material scientists.

Energy conversion and storage applications of graphene, phosphorene and Mxene

Photovoltaic (PV) devices such as GaAs, GaInP, organic and perovskite solar cells are highly desirable for harvesting ambient light energy and generating small amounts of power sufficient to run rechargeable batteries and sensors1. However, accurate test methods for measuring the electrical performance parameters of these devices under artificial light sources such as light emitting diodes, incandescent, or fluorescent lighting are lacking. Furthermore, fundamental energy loss mechanisms under these non-conventional lighting sources are not well understood.2,3 In this work, we describe the methodology and results of an accurate, reference-solar-cell-based method for measuring the current vs voltage (I-V) characteristics of solar cells under a variety of unique ambient light sources at an illuminance of 1000 lx or less. We describe some unexpected findings with implications for accurate characterization, such as sub-bandgap spectral effects in solar cells grown on heterosubstrates, and we unambiguously show how power conversion efficiency can be accurately determined. Additionally, we use absolute electroluminescence measurements to compute nonradiative recombination losses in these cells and, with additional energy loss calculations, display a clear picture of the balance of energy within each cell under unique ambient lighting conditions.

Measuring and understanding PV performance under ambient lighting

This study explores the sustainable feasibility of kitchen waste extract as a photosensitizer for Dye Sensitized Solar Cell (DSSC). The dye was extracted from Onion peels by conventional soaking method. The dye extract was characterized by Thin Layer Chromatography (TLC) and UV-Visible spectroscopy at room temperature. These characterizations technique indicates anthocyanin pigment in the extracted dye from the Onion peel. The maximum absorbance was found at wavelength 533nm in the UV-Visible spectra with direct band gap (Eg) at 2.14eV from Tauc plot and Eg = 2.2eV from numerical derivative dA/dE as well. This crude extract was used as a photosensitizer in DSSC. This DSSC was characterized by using Keithley 2450 Source Meter in presence of tungsten bulb illumination. The key performance parameters were also computed i.e., short circuit current (ISC = 2.42 𝜇𝐴), open-circuit voltage (Voc = 0.51 mV), fill factor (FF = 0.27) and efficiency ( 𝜂 = 3.8〖×10〗^(−5) %) under tungsten bulb illumination without giving any pre-treatment to the components of DSSC. 



Utilization of kitchen waste (Onion peels) as photosensitizer for Dye Sensitized Solar Cell

An efficient AlGaN-based Far-UVC (222 nm) light-emitting diodes (LEDs) for the disinfection of SARS-CoV-2 (Coronavirus) are designed in this study. The simulation results show the remarkable optoelectronic performance of the proposed LEDs. Based on our results, we highly believe that this study providing a new approach for the development of efficient Far-UVC (222 nm) LEDs, which is a promising candidate for the disinfection of severe SARS-CoV-2 (Coronavirus).

Designing 222 nm III-Nitride-based Far UVC LEDs for the disinfection of SARS-2 (Covid-19)

The present work reports a facile synthesis method to produce reduced graphene oxide/polyaniline (rGO/PANI) nanocomposites via a simple in-situ polymerization of aniline monomer in acid solution and later reoxidation of polyaniline by heavy oxidant. The Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) results endorsed the formation of high quality rGO/PANI nanocomposite. The electrochemical properties of the rGO/PANI nanocomposites as supercapacitor materials were investigated. The cyclic voltammetry (CV) of rGO/PANI nanocomposites showed that in general, specific capacitance reduces with increasing scan rate within the range (10 – 100 mV/s). The fabricated rGO/PANI nanocomposites showed high specific capacitance as compared to PANI and rGO. The improved electrochemical performance suggests promising application of the rGO/PANI nanocomposites in high performance supercapacitors.


Synthesis of reduced graphene oxide/polyaniline nanocomposites for high performance supercapacitors

In the journey to Net-Zero, it is becoming increasingly evident that hydrogen (H2) technologies will play an important role. The energy transition is already taking shape with electrification and H2 technologies being the main drivers. To ensure that H2 technologies increase their contribution and share in a sustainable and reliable future energy system, it is imperative that the research, development and deployment (RD&D) challenges facing H2 technologies are addressed. 
This presentation reviews the current and future RD&D needs and gaps given their importance in bringing about a long-awaited H2 economy. RD&D opportunities for a global scale-up and use of H2 technologies are identified and discussed. They cover the entire H2 value chain, from production and storage to distribution and end uses, and span the entire technology readiness level (TRL) spectrum. Our review also shows the many opportunities for RD&D collaboration involving both public and private sectors, locally as well as globally.

Research, development and deployment needs and opportunities for a massive deployment of hydrogen technologies

In this work, anisotropic ambipolar (p x n)-type TTE materials are classified and analyzed theoretically according to positive or negative band gap, and the position of the Fermi energy relative to the respective band edges.

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Full Experimental Seebeck Tensor Characterization for (p × n)-Type Transverse Thermoelectrics

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