Periodic Reporting for period 1 - Hi-BITS (High efficiency bifacial thin film chalcogenide solar cells)
Période du rapport: 2023-10-01 au 2025-03-31
CIGS solar cells currently reach 23% efficiency with a metallic back contact and a >2µm thick absorber layer as well as excellent stability. Hi-BITS partners will introduce a disruptive device structure that allows a high degree of bifaciality and photon recycling. The efficiency will be improved beyond 25% by the innovative high quality CIGS absorbers and passivation at the back contact, which allows to remove compositional gradients and reduce absorber thickness. Hi-BITS will explore four different applications, that all use these features, including bi-faciality, flexible and reflective, semi-transparency and suitability for tandems. While the bi-faciality will harvest stray light reflected from the ground, and thereby increase the yearly yield, the reflective and flexible will enable photon recycling for light-weight modules. The necessary back reflector is easily integrated into the bifacial Hi-BITS cells. To close the gap in efficiency between large area modules and record cells, Hi-BITS will improve monolithic integration to increase the productive area of the module, and the semi-conductor quality by fast-feed-back methods fit for industrial processes. The applications foreseen as results from Hi-BITS respond to market demands and are particularly well suited for building or vehicle integration or agriphotovoltaics. Modules for these new applications will be out-door tested in three different European climates demonstrating higher energy yield and stability. Life cycle analysis and costing, taking aspects of circularity into account, will underline the superior sustainability of these new modules. Hi-BITS includes 5 European PV manufacturers, will improve a technology that does not depend on imports of ingots or wafers, reinforcing the European PV value chain. The results will boost thin-film manufacturing by higher efficiency, lower raw material consumption, shorter and well-controlled processes, better module technologies and novel applications.
During the first reporting period of the Hi-BITS project (month 1 to month 18), the consortium met in four General Assemblies in hybrid meetings with a large in-person attendance. In addition to the General Assemblies, consortium members have met in on-line WP meetings approximately every two months, complemented by some dedicated online workshops and task meetings. In bi-monthly Steering Committee meetings (online), the work package leaders present brief progress reports and discuss the general progress of the project, including risk assessment and planning of upcoming tasks and activities.
WP1 established the project’s management structure, operational procedures, and data handling protocols. A sample tracking system was implemented to coordinate exchanges between partners. Project management guidelines were defined, covering governance, reporting, risk management, and communication tools. A Data Management Plan was delivered, outlining data types, FAIR principles, and IP considerations. Regular Steering Committee (bi-monthly) and General Assembly (every six months) meetings were conducted to monitor progress and address risks. All deliverables and milestones were completed according to schedule.
WP2 focused on the development and modeling of rear contact and passivation layers for bifacial and ultrathin CIGS solar cells. Optical and electro-optical simulations were used to optimize nanostructured back contacts and light-trapping schemes, achieving improved absorption and current density. Transparent conductive oxides (TCOs) such as ITO, InZrO, and IOH were evaluated, with IOH and InZrO showing superior optical properties. Bi-layer TCO substrates were optimized, and advanced passivation strategies, including nanoimprinted SiO2 point contacts and CuInSe2/GaOₓ hole transport layers, demonstrated improved device performance. Transparent back contacts were delivered to WP3, and all modeling input parameters were compiled and shared.
WP3 focused on developing and characterizing CIGS solar cells with bifacial, reflective, and semi-transparent architectures. CIGS absorbers were optimized for compatibility with transparent and reflective back contacts, with adjustments to deposition processes and interface treatments. Advanced characterization techniques were applied to assess passivation, recombination losses, and structural properties. Bifacial devices achieved up to 17.6% efficiency under front illumination and bifaciality factors up to 75%. Reflective back contacts demonstrated optical gains, and semi-transparent devices with 50% AVT were fabricated using both top-down and bottom-up approaches. All developments supported integration with WP2 components and informed further optimization.
WP4 addressed strategies to minimize efficiency losses during module integration and to enable process monitoring. Laser-based scribing methods for cell interconnection were developed and demonstrated in prototype modules, with further optimization needed for reproducibility. Transparent conductive oxide (TCO) layers combined with grid lines were designed to reduce optical and resistive losses. Encapsulation concepts using ALD-deposited alumina were proposed for improved moisture resistance in flexible modules. In-line monitoring methodologies were developed using optical and machine learning techniques to assess Mo:Na layer thickness and absorber stoichiometry, showing high accuracy and potential for real-time quality control.
WP5 addresses the transition from lab-scale developments to application-specific module prototypes. This WP was only active for one month in reporting period 1. Initial activities included coordination meetings and the creation of a detailed sample flow chart to guide fabrication steps for the four targeted applications: bifacial, reflective, semi-transparent, and tandem modules.
Likewise, WP6 also started in month 18 with preparatory activities focused on defining protocols for outdoor performance monitoring of CIGS modules. Relevant international standards and guidelines were identified, and test site upgrades were initiated, including acquisition of standardized monitoring equipment.
WP7 focused on life cycle assessment (LCA) and sustainability screening of Hi-BITS module components. Initial results showed that new functional layers have minor environmental impact compared to absorber growth and glass components. LCA models were developed using updated datasets and implemented in openLCA, with cradle-to-gate and cradle-to-cradle system boundaries. Preliminary comparisons indicate that CIGS modules may have a lower carbon footprint than other PV technologies. Preparations for life cycle costing and circularity assessment were initiated, with further data collection and model refinement planned for the next period.
WP8 addresses increasing project visibility, stakeholder engagement, and preparing for future exploitation of results. A project website and LinkedIn presence were established, alongside newsletters, videos, and media coverage. A dissemination and communication plan was implemented. Stakeholder mapping and participation in events supported collaboration and awareness.
WP1 established the project’s management structure, operational procedures, and data handling protocols. A sample tracking system was implemented to coordinate exchanges between partners. Project management guidelines were defined, covering governance, reporting, risk management, and communication tools. A Data Management Plan was delivered, outlining data types, FAIR principles, and IP considerations. Regular Steering Committee (bi-monthly) and General Assembly (every six months) meetings were conducted to monitor progress and address risks. All deliverables and milestones were completed according to schedule.
WP2 focused on the development and modeling of rear contact and passivation layers for bifacial and ultrathin CIGS solar cells. Optical and electro-optical simulations were used to optimize nanostructured back contacts and light-trapping schemes, achieving improved absorption and current density. Transparent conductive oxides (TCOs) such as ITO, InZrO, and IOH were evaluated, with IOH and InZrO showing superior optical properties. Bi-layer TCO substrates were optimized, and advanced passivation strategies, including nanoimprinted SiO2 point contacts and CuInSe2/GaOₓ hole transport layers, demonstrated improved device performance. Transparent back contacts were delivered to WP3, and all modeling input parameters were compiled and shared.
WP3 focused on developing and characterizing CIGS solar cells with bifacial, reflective, and semi-transparent architectures. CIGS absorbers were optimized for compatibility with transparent and reflective back contacts, with adjustments to deposition processes and interface treatments. Advanced characterization techniques were applied to assess passivation, recombination losses, and structural properties. Bifacial devices achieved up to 17.6% efficiency under front illumination and bifaciality factors up to 75%. Reflective back contacts demonstrated optical gains, and semi-transparent devices with 50% AVT were fabricated using both top-down and bottom-up approaches. All developments supported integration with WP2 components and informed further optimization.
WP4 addressed strategies to minimize efficiency losses during module integration and to enable process monitoring. Laser-based scribing methods for cell interconnection were developed and demonstrated in prototype modules, with further optimization needed for reproducibility. Transparent conductive oxide (TCO) layers combined with grid lines were designed to reduce optical and resistive losses. Encapsulation concepts using ALD-deposited alumina were proposed for improved moisture resistance in flexible modules. In-line monitoring methodologies were developed using optical and machine learning techniques to assess Mo:Na layer thickness and absorber stoichiometry, showing high accuracy and potential for real-time quality control.
WP5 addresses the transition from lab-scale developments to application-specific module prototypes. This WP was only active for one month in reporting period 1. Initial activities included coordination meetings and the creation of a detailed sample flow chart to guide fabrication steps for the four targeted applications: bifacial, reflective, semi-transparent, and tandem modules.
Likewise, WP6 also started in month 18 with preparatory activities focused on defining protocols for outdoor performance monitoring of CIGS modules. Relevant international standards and guidelines were identified, and test site upgrades were initiated, including acquisition of standardized monitoring equipment.
WP7 focused on life cycle assessment (LCA) and sustainability screening of Hi-BITS module components. Initial results showed that new functional layers have minor environmental impact compared to absorber growth and glass components. LCA models were developed using updated datasets and implemented in openLCA, with cradle-to-gate and cradle-to-cradle system boundaries. Preliminary comparisons indicate that CIGS modules may have a lower carbon footprint than other PV technologies. Preparations for life cycle costing and circularity assessment were initiated, with further data collection and model refinement planned for the next period.
WP8 addresses increasing project visibility, stakeholder engagement, and preparing for future exploitation of results. A project website and LinkedIn presence were established, alongside newsletters, videos, and media coverage. A dissemination and communication plan was implemented. Stakeholder mapping and participation in events supported collaboration and awareness.