The development activities (growth, characterization and post growth processes) of new multi-junction 4J InGaP\/InGaAs\/Ge\/T\/Ge three-terminal (3T) cell architectures with transistor effect are reported. Anti-reflective coatings with a graded refractive index, front metal grids with triangular profile and measurement systems and procedures for the electro-optical characterization of 3T devices have been developed too.<\/p>\n","protected":false},"author":93,"featured_media":0,"comment_status":"open","ping_status":"closed","template":"","meta":{"_acf_changed":false,"footnotes":""},"tags":[1374,1300,1312,1328],"targets":[1304,1317],"rapporti_tipologie":[762],"class_list":["post-209406","rapporti","type-rapporti","status-publish","hentry","tag-concentrator-photovoltaics","tag-industrial-sector","tag-innovation","tag-photovoltaics","targets-industrial-world","targets-research","rapporti_tipologie-report-en"],"acf":{"dont_show_hompage":true,"projects":{"ID":188400,"post_author":"464","post_date":"2024-06-13 15:10:01","post_date_gmt":"2024-06-13 13:10:01","post_content":"","post_title":"Integrated High Efficiency Photovoltaic Project","post_excerpt":"The goal of this project is to facilitate the development of high-efficiency, low-cost photovoltaic (PV) generation systems, while helping to maximize the energy production of the plants in Italy.","post_status":"publish","comment_status":"open","ping_status":"closed","post_password":"","post_name":"integrated-high-efficiency-photovoltaic-project","to_ping":"","pinged":"","post_modified":"2024-07-03 11:13:04","post_modified_gmt":"2024-07-03 09:13:04","post_content_filtered":"","post_parent":0,"guid":"https:\/\/www.rse-web.it\/progetti\/integrated-high-efficiency-photovoltaic-project\/","menu_order":0,"post_type":"progetti","post_mime_type":"","comment_count":"0","filter":"raw"},"order_posts":"","dont_show_search":false,"related_posts":false,"show_on_slider":false,"single_post_data":{"titolo_spot":"","post_content":"
In continuity with the previous research period, we implemented the development activity on MJ junction cells based on III-V and IV compounds, in which new cell architectures were explored. A first functional device with four junctions (4J) InGaP\/InGaAs\/Ge\/Ge has been developed. It was obtained by depositing all the layers in the same MOVPE growth chamber and with a new design which considers a three-terminal (3T) cell architecture, in which the two Ge junctions can interact through the transistor effect.<\/p>\n
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The functional device was manufactured using only frontal “busbar” contacts. Despite this simplification, the upper 3J part (InGaP\/InGaAs\/Ge) of the 4J functional device presented an efficiency value of 24%, with AM1.5d-ASTM-G173-3 spectrum (1000 W\/m2). Using a metal grid, the value can be extrapolated to 27% and this a value results equal to the efficiency value measured for a 3J – InGaP\/InGaAs\/Ge cell, with the same structure, but deposited in a MOVPE growth chamber free of contamination from the group IV elements. The lower Ge cell of the 4J device instead showed an efficiency value of 2.15% higher than the theoretical one of 1.48%, thanks to the transistor effect which is not yet foreseen in current simulation models.<\/p>\n
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The results achieved have a high technological and scientific value. By depositing the entire structure of the MJ device inside the same MOVPE growth chamber, RSE has demonstrated that it is possible to overcome the problem of “cross contamination” between elements III-V and IV which had until now hindered a commercially competitive technological path for such devices. The 4J device also has a new architecture that exploits the “transistor effect” in an innovative way, to transfer power from the upper Ge junction to the lower Ge one. In this way, the mismatch between the currents produced in the upper part of the 4J device, i.e., in the 3J-InGaP\/GaAs\/Ge part, is almost eliminated, while an increase in the quantum efficiency is obtained in the lower Ge junction, which allows to increase the conversion efficiency of the MJ device.<\/p>\n
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The report describes the MOVPE deposition, optimized in a temperature range between 460\u00b0C and 590\u00b0C, and \u201cpost growth\u201d processes that enabled the manufacturing of the 4J InGaP\/GaAs\/Ge\/T\/Ge-3T device. The lithographic process is described, as well as the chemical etching process for the development of the “third” terminal, the deposition of metals, considering the design of front metal grids with triangular geometry rather than rectangular ones, and the simulation and development of innovative anti-reflective coatings with a gradual refractive index. The diagnostic techniques proposed for the characterization of the MJ device are also described.<\/p>\n
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Quantum efficiency and current-voltage measurements never carried out on this type of device required intense characterization activity to identify the necessary light and electrical polarization conditions. The results obtained, on one hand, pave the way for the development of more efficient solar cells that exploit III-V and group IV elements, on the other hand, indicate the need to develop new performance simulation programs that include the transistor effect to expand the combination of materials with different energy gaps and obtain newly developed MJ solar cells.<\/p>\n
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The Report is available on the Italian site<\/strong><\/p>\n","link_estreno":false,"scarica_file":false,"button":{"text":"","link":""},"referente_group":false,"data_emissione":"2024-12-31","autori":"G. Timo\u00b4, E. Achilli, F. Annoni, N. Armani, M. Calicchio, M. Cornelli, M. V. Imperatore, E. Malvisi, F. Trespidi (RSE S.p.A.)","rapporto":"","rif_rse":"24013434"},"satellite_post_url":""},"yoast_head":"\n