Final Report Summary - KESTCELLS (Training for sustainable low cost PV technologies: development of kesterite based efficient solar cells)
In the SET-Plan one of the objectives for 2020 was to ensure a sustainable increase of the production of energy through renewable sources, in which low cost thin film PV devices would play a central role. This kind of technology based on Cu2ZnSn(S,Se)4 (CZTSSe) is also known as kesterites and it offers low consumption of raw materials, highly automated and efficient manufacturing processes, low carbon footprint and better performances at elevated temperatures than the standard counterparts. However, the academic institutions able to train new researchers in this field are limited due to the multidisciplinary approach necessary to get highly skilled professionals. Actually, the availability of these researchers was identified as one of the potential bottlenecks which could condition the further development of this technology in the mid- and long-term. KESTCELLS project, which has been built on the close efforts of three research centres, six universities and two industrial companies, has actively worked to provide a significant advance in the development of new kesterite based solar cells with improved characteristics and efficiencies beyond the 10% threshold, and to train 14 new high level researchers on this topic, validating the feasibility of the training program developed by the Consortium.
From a scientific point of view the main achievement is that as far as technical aspects are concerned, CZTSSe has been identified as one of the most promising material for future thin films PV applications, which meets the requirements of abundance of the constituent elements, low toxicity level and a full compatibility with the standard processes employed for the PV community at present time. As a result, kesterites are now considered a potential alternative at medium and long term to the conventional CIGS technology, which presents the inherent problem of In and Ga scarcity. In the frame of the project, the fundamental properties of kesterites have been studied using different advanced characterization methods, including X-ray and neutron diffraction, Raman spectroscopy, photoluminescence and ellipsometry. In this sense, KESTCELLS has largely contributed to understand basic and applied characteristics of these materials such as the band-gap properties, the energetic position of the bands and ionisation energy of defects, the crystal structure and the structural origin of intrinsic point defects and the fundamental vibrational properties, as well as their dependence on the compound composition and growth process. This has been a significant step forward in the fundamental knowledge of kesterites. The project has also developed different approaches for the synthesis of high quality kesterite layers, which combined with the advancements on the re-design and optimization of the device structure, has allowed achieving solar cells with efficiencies in the range of 9-11%, and a record value of 11.8%. The project has also laid the foundations for the identification of characterization methods suitable for future development of on-line quality control tools, as well as the availability of a complete 2D model for the simulation of kesterite based devices. All these research activities have been complemented with the analysis of future industrialization of the technology.
In parallel, KESTCELLS has trained fourteen researchers through a customized programme, designed in accordance to each fellow needs. Fifty-six specific seminars, five specialized workshops, eight project meetings, two business schools, one summer school in photovoltaics, ten open day activities, three newsletters, twelve video-clips, and thirty-eight secondments have been implemented during the project, which demonstrates an outstanding training effort at network level. Thanks to all these activities, a broad training that goes beyond the scope that each institution is able to offer with own resources has been feasible. In consequence the fellows have received a notable training focused on scientific aspects and complementary soft-skills in management, IPR, communication, writing, reporting, business creation, entrepreneurship and others. The success of the training is validated by the large number of outputs generated, which include 147 contributions at international conferences (invited conferences, key note speeches, oral and poster presentations), and 82 papers in peer-reviewed journals.
In summary, KESTCELLS has demonstrated the potential of the kesterites based solar cells technology, increasing the TRL from 2 (basic technological research) at the beginning of the project, to 4 (validation at a laboratory level) at the end. Through an effective and fruitful scientific collaboration between research centers, universities and companies, most of the KESTCELLS’ ESRs have completed Doctoral Degrees enriched with a multidisciplinary training paying special attention to industrial aspects and interests. All in all, the project represents a step towards more integrated collaborative schemes in PV at EU level.
www.kestcells.eu
Contact Person: Dr. Edgardo Saucedo (esaucedo@irec.cat)
From a scientific point of view the main achievement is that as far as technical aspects are concerned, CZTSSe has been identified as one of the most promising material for future thin films PV applications, which meets the requirements of abundance of the constituent elements, low toxicity level and a full compatibility with the standard processes employed for the PV community at present time. As a result, kesterites are now considered a potential alternative at medium and long term to the conventional CIGS technology, which presents the inherent problem of In and Ga scarcity. In the frame of the project, the fundamental properties of kesterites have been studied using different advanced characterization methods, including X-ray and neutron diffraction, Raman spectroscopy, photoluminescence and ellipsometry. In this sense, KESTCELLS has largely contributed to understand basic and applied characteristics of these materials such as the band-gap properties, the energetic position of the bands and ionisation energy of defects, the crystal structure and the structural origin of intrinsic point defects and the fundamental vibrational properties, as well as their dependence on the compound composition and growth process. This has been a significant step forward in the fundamental knowledge of kesterites. The project has also developed different approaches for the synthesis of high quality kesterite layers, which combined with the advancements on the re-design and optimization of the device structure, has allowed achieving solar cells with efficiencies in the range of 9-11%, and a record value of 11.8%. The project has also laid the foundations for the identification of characterization methods suitable for future development of on-line quality control tools, as well as the availability of a complete 2D model for the simulation of kesterite based devices. All these research activities have been complemented with the analysis of future industrialization of the technology.
In parallel, KESTCELLS has trained fourteen researchers through a customized programme, designed in accordance to each fellow needs. Fifty-six specific seminars, five specialized workshops, eight project meetings, two business schools, one summer school in photovoltaics, ten open day activities, three newsletters, twelve video-clips, and thirty-eight secondments have been implemented during the project, which demonstrates an outstanding training effort at network level. Thanks to all these activities, a broad training that goes beyond the scope that each institution is able to offer with own resources has been feasible. In consequence the fellows have received a notable training focused on scientific aspects and complementary soft-skills in management, IPR, communication, writing, reporting, business creation, entrepreneurship and others. The success of the training is validated by the large number of outputs generated, which include 147 contributions at international conferences (invited conferences, key note speeches, oral and poster presentations), and 82 papers in peer-reviewed journals.
In summary, KESTCELLS has demonstrated the potential of the kesterites based solar cells technology, increasing the TRL from 2 (basic technological research) at the beginning of the project, to 4 (validation at a laboratory level) at the end. Through an effective and fruitful scientific collaboration between research centers, universities and companies, most of the KESTCELLS’ ESRs have completed Doctoral Degrees enriched with a multidisciplinary training paying special attention to industrial aspects and interests. All in all, the project represents a step towards more integrated collaborative schemes in PV at EU level.
www.kestcells.eu
Contact Person: Dr. Edgardo Saucedo (esaucedo@irec.cat)