Advanced Strategies for Development of Sustainable Semiconductors for Scalable Solar Cell Applications

Project Information

SOLARUP

Grant agreement ID: 101046297

DOI

10.3030/101046297

EC signature date 7 July 2022

Start date 1 October 2022

End date 30 September 2026

Funded under

• The European Innovation Council (EIC)

Total cost

€ 2 930 127,50

EU contribution

€ 2 930 127,50

Coordinated by

FUNDACIO INSTITUT CATALA DE NANOCIENCIA I NANOTECNOLOGIA
Spain

Periodic Reporting for period 2 - SOLARUP (Advanced Strategies for Development of Sustainable Semiconductors for Scalable Solar Cell Applications)

Reporting period: 2023-10-01 to 2025-03-31

Summary of the context and overall objectives of the project

SOLARUP aims to demonstrate an ultra-thin nanostructured solar cell based on zinc phosphide (Zn3P2) with unprecedented conversion efficiencies. Zn3P2 is an earth-abundant, direct bandgap semiconductor with the potential to bridge the gap between efficiency, scalability and recyclability, providing a breakthrough technological solution that can revolutionize modern PV. This technology will be cost-effective, scalable and suitable for use in the above-described scenarios. It will also be delivered as part of a full life cycle strategy to ensure sustainability and recyclability at end-of-life.
The specific scientific objectives of SOLARUP are:
O1. Engineer the fundamental properties of Zn3P2 which determine its optoelectronic behaviour.
O2. Identify the main doping mechanisms responsible for p-type conductivity of Zn3P2 and develop suitable processes for its control, both intrinsic and extrinsic.
O3. Design novel Zn3P2 based solar cell architecture, which will decrease losses, increase durability and achieve high solar cell efficiency.
O4. Scale-up the lateral epitaxial growth process to full wafers to create (virtually) free-standing Zn3P2 absorber layers industrially compatible at the mass production level (2” wafers scale thin films), using low environmental impact processes and demonstrate full lift-off by exfoliation of the Zn3P2 layer for substrate recyclability.
O5. Perform a LCA to show evidence of: (i) lower environmental impact; (ii) better resource efficiency than current commercial PV technologies; and (iii) circularity potential. Investigate the economic feasibility of the PV and the recycling process for the full solar cell by assessing major cost drivers such as material costs, production process, efficiency, device lifetime and (by)product value.
The project presents a new system archetype and a full-cycle material strategy for PV, which will propel a paradigm shift in modern PV research. Our final prototype aims to convince the PV industry of the value of introducing zinc phosphide in their innovation line.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

• Summary of progress towards the achievement of each of the project objectives:
O1. By now, the growth has been successfully achieved on InP and efforts are being done in order to successfully grow the films on top of graphene or silicon substrates. Efforts have been also made in order to control the microstructure and improve the PV properties (carrier density and electrical transport) by selecting the appropriate Zn/P ratio.
O2. We are performing DFT calculations in order to unravel the structure, formation and ionization energies, and equilibrium concentrations of intrinsic point defects and investigate their effects on the stability, electronic and optical properties of Zn3P2. In addition, we have started to work on the screening of elements for potential extrinsic doping of Zn3P2.
O3. The PV device design and simulations have started as part of WP4. We have started to work on the device design in order to predict the performance of different layer combinations, following two main pathways: p-n junction and selective contacts.
O4. We have evaluated the different substrate processing techniques, and currently working on implementing them on indium phosphide and silicon wafers for subsequent growth experiments.
O5. By now, the life cycle assessment is on schedule, we have been able to submit the related deliverables (D5.1. LCA Goal & Scope report).

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

• Progress of the project towards delivering scientific impact, based on its objectives.
By now, the growth has been successfully achieved on InP and efforts are being done in order to successfully grow the films on top of graphene or silicon substrates. We have published 3 articles:

- E. Z. Stutz, et al., Faraday Discussions, 239, 202-218 (2022)
- R. Paul, et al., Solar Energy Materials and Solar Cells, 252, 112194 (2023)
- R. Paul, et al., Solar Energy Materials and Solar Cells, 256, 112349 (2023)

We will organize a Symposium at the next E-MRS Spring Meeting 2024 (Strasbourg, France): Symposium Q: “Future Photovoltaics based on Earth Abundant Materials”
In this symposium we plan to invite stakeholders, researchers and industry members to share and discuss about the proposed developments we are planning.

SOLARUP partners answers to the Innovation Radar Questionnaire identify 7 possible Innovations with potential for exploitation:
1. Eco-design for zinc phosphide based solar cell
2. Method for scaling selective area epitaxy for earth-abundant photovoltaic absorber materials
3. Method to obtain zinc phosphide on earth-abundant wafers
4. Surface preparation (it can be treatment, step density etc) of graphene surfaces for high quality deposition of zinc phosphide
5. Solar cell device from a thin film obtained on graphene
6. Method to transfer thin films obtained by selective area epitaxy on InP or any other substrate and reuse of the substrate
7. Application of premise for prospective Life cycle assessment using integrated assessment models (IAM)
Beyond these routes to impact, we are also establishing a clear roadmap for sustainability in PV, defining practices that can be incorporated/adapted for all future solar technologies.

SOLARUP has generated a network of highly trained researchers in advanced PV technologies, including 5 new PhDs (1 female and 4 males) and 2 postdocs (1 female and 1 male).

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