Faculdade

Eventos

Seminários - Prof. Eugene A. Katz & Prof. Killiam Lobato

Qua, 20/07/2022 - 11:00 - 13:00
Tipo de evento: 
Actividade Cultural
Tipo de evento: 
Seminário
Organizador: 
CENIMAT
Local do evento: 
UNINOVA ed.1
Localização específica: 
Auditório UNINOVA
Divulgação | Seminários
 
"Ultra-efficient photovoltaics: Solar concentration vs external photon recycling" por Prof. Eugene A. Katz (The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Israel)
Data|Hora: 20.Julho.2022 | 11H00
Local: Edifício do UNINOVA 1
Abstract (HERE): The maximum efficiency of any solar cell (so-called Shockley-Queisser limit) can be evaluated in terms of its ability to emit light in open circuit (OC) and to quench the luminescence in short circuit (SC) [1-2]. In my lecture I will review the basic principles of ultra-high efficient photovoltaics (PV) as well as their experimental realization using optical concentration of sunlight [3 - 6] and external photon recycling [7]. I will also discuss the results of our theoretical analysis [8-9] and the experimental evidence [10-11] that solar cells operated at ultra-high solar concentrations can be more tolerant to elevated temperatures. Based on thes results, an approach for a hybrid concentrating PV-thermal absorber operating at high solar concentration and at the high temperatures (673–873 K, suitable to efficient commercial steam turbines) will be suggested [12]. Such hybrid solar electricity generation can combine the high PV efficiency with the dispatchability of solarthermal power plants.
-----------------------------------------------------------------------------------
"Two examples of laser processing as a scalable technique for energy applications: Tunnel junctions for tandem solar cells and ionic transport enhancement in supercapacitors" por Prof. Killiam Lobato (Assistant Professor in the area of Energy Engineering, FCT-UNL)
Data|Hora: 20.Julho.2022 | 12H00
Local: Edifício do UNINOVA 1
Abstract (HERE): Most energy conversion and storage materials and devices must be efficient, low-cost and manufactured at enormous scales. Efficient devices have a typical active thicknesses between 1 to 500 microns (z direction). However, these must be produced on large areas (up to several m2) with a minimal variation in the film properties and composition in the z-direction. In essence, microelectronics (and nano!)is applied to the x-y macroscale. Lasers have come a long way since their invention and are now ubiquitous in R&D and industrial environments. This talk will focus on how lasers are being used to form tunnel junctions for perovskite on silicon tandem solar cells, and on modifying carbon supercapacitor electrodes. Gas Immersion Laser Doping (GILD) is a technique which permits the doping of semiconductors high doping concentrations and abrupt changes in doping concentration – requirements for tunnel junctions. We will discuss our recent progress in adapting this technique to be scalable and applicable fortandem perovskite on silicon solar cells. A limitation of supercapacitor electrodes is that their energy density decreases at high power densities. This is a result of impaired ionic transport,reducing the effective capacity area. Laser ablation has been used to create ionic channels in carbon based porous which enables fasterionic transport through the supercapacitor electrode and hence faster charging and discharging currents,resulting in higher specific power and energy densities of supercapacitor electrodes.