Periodic Reporting for period 1 - C2C-PV (Cradle-to-Cradle Design of Photovoltaic Modules)
Période du rapport: 2023-09-01 au 2026-02-28
The C2C-PV (Cradle-to-Cradle Photovoltaics) project aims to redefine how solar modules are designed, built, and recycled. Conventional photovoltaic technologies have achieved remarkable efficiency and cost reductions, yet their production and disposal still follow a linear industrial logic: materials are extracted, processed, used once, and discarded. This approach is unsustainable as the world moves toward multi-terawatt solar capacity, where millions of tons of modules will eventually reach end-of-life.
C2C-PV proposes a fundamental design transition—from “design for immortality,” which maximizes single-cycle durability, to “design for recycling,” in which every material layer and process step has a predefined path for safe disassembly and reuse. The project’s goal is to create the scientific and technological foundations of a circular photovoltaic economy, ensuring that solar energy remains truly renewable not only in operation but also in its material life cycle.
To reach this goal, the project integrates three disciplines:
1. Materials science, to identify and qualify recyclable, non-toxic materials suitable for photovoltaic use.
2. Interface engineering, to develop device architectures that allow layer-by-layer separation without contamination or loss of function.
3. Sustainability and techno-economic modelling, to quantify environmental and financial performance over multiple product generations.
The vision is to demonstrate that a photovoltaic module can be recycled repeatedly, maintaining high performance, low cost, and minimal environmental impact—a solar cell designed for perpetual utility.
C2C-PV proposes a fundamental design transition—from “design for immortality,” which maximizes single-cycle durability, to “design for recycling,” in which every material layer and process step has a predefined path for safe disassembly and reuse. The project’s goal is to create the scientific and technological foundations of a circular photovoltaic economy, ensuring that solar energy remains truly renewable not only in operation but also in its material life cycle.
To reach this goal, the project integrates three disciplines:
1. Materials science, to identify and qualify recyclable, non-toxic materials suitable for photovoltaic use.
2. Interface engineering, to develop device architectures that allow layer-by-layer separation without contamination or loss of function.
3. Sustainability and techno-economic modelling, to quantify environmental and financial performance over multiple product generations.
The vision is to demonstrate that a photovoltaic module can be recycled repeatedly, maintaining high performance, low cost, and minimal environmental impact—a solar cell designed for perpetual utility.
During the first project phase, C2C-PV achieved several key scientific and technological milestones:
1. Establishing a common material pool.
A database of photovoltaic materials was created to evaluate their suitability for circular use. The concept is based on integrating PV materials into a broader industrial ecosystem, so that glass, metals, and polymers used in solar modules can also circulate through other product cycles. The accompanying analysis, published as “Cradle-to-cradle recycling in terawatt photovoltaics: A vision of perpetual utility” (Peters et al., Joule 2024), demonstrated that the PV industry will soon become a major consumer of several essential materials such as glass, aluminum, and silver. This finding highlights the necessity of circular recycling to sustain global deployment. Current work extends this model to perovskite solar technologies and identifies materials that can be reused across product generations.
2. Developing interfaces for separability.
Reconciling durability with ease of disassembly emerged as the core scientific challenge. C2C-PV developed a bio-based sacrificial edge seal combined with a gel-type encapsulant, allowing modules to be opened and resealed without damage—an innovation now protected by patent. At the device level, the team demonstrated the first fully recyclable perovskite solar cell, where each layer can be selectively dissolved using orthogonal solvents. The results, published in “Closing the loop: recycling of MAPbI₃ perovskite solar cells” (Wu et al., Energy & Environmental Science 2024), achieved 99.97 % mass recovery with identical efficiency after reuse—proof of concept for rapid, clean closed-loop recycling.
3. Creating a unified design framework.
The conceptual and quantitative design space for recyclable solar cells was formalized in “The Ideal Recyclable Solar Cell” (Peters & Brabec, Nature Reviews Chemistry 2025). This work introduces measurable parameters—intra-layer bonding, inter-layer bonding, bonding contrast, and locked-in entropy—to describe the trade-offs between performance, stability, and recyclability. It provides the first theoretical framework for assessing recyclability in photovoltaic materials and has since been adopted by other research groups in the field.
4. Prototyping recyclable module envelopes.
Modules built with the new edge-seal design were shown to be reusable: after separation, the glass package could be resealed, maintaining full moisture protection and mechanical integrity. Devices encapsulated in this reusable structure exhibited the same operational stability as conventional references, confirming the practical feasibility of circular module construction.
5. Economic and environmental validation.
Techno-economic models demonstrated that recycling substrates and solvents can reduce material costs by more than 60 % at both laboratory and industrial scale. Life-cycle assessments showed a 70 % reduction in energy payback time and greenhouse-gas emissions compared with conventional fabrication. These findings confirm that C2C design is not only environmentally beneficial but also economically attractive.
6. Outreach and recognition.
The project’s results have been featured in major media outlets, science podcasts, and a German television documentary on recycling. Two patents were filed, and the PI and team have been invited to multiple international conferences, including EU PVSEC, IEEE PVSC, and MRS, establishing C2C-PV as a reference initiative in circular photovoltaics.
1. Establishing a common material pool.
A database of photovoltaic materials was created to evaluate their suitability for circular use. The concept is based on integrating PV materials into a broader industrial ecosystem, so that glass, metals, and polymers used in solar modules can also circulate through other product cycles. The accompanying analysis, published as “Cradle-to-cradle recycling in terawatt photovoltaics: A vision of perpetual utility” (Peters et al., Joule 2024), demonstrated that the PV industry will soon become a major consumer of several essential materials such as glass, aluminum, and silver. This finding highlights the necessity of circular recycling to sustain global deployment. Current work extends this model to perovskite solar technologies and identifies materials that can be reused across product generations.
2. Developing interfaces for separability.
Reconciling durability with ease of disassembly emerged as the core scientific challenge. C2C-PV developed a bio-based sacrificial edge seal combined with a gel-type encapsulant, allowing modules to be opened and resealed without damage—an innovation now protected by patent. At the device level, the team demonstrated the first fully recyclable perovskite solar cell, where each layer can be selectively dissolved using orthogonal solvents. The results, published in “Closing the loop: recycling of MAPbI₃ perovskite solar cells” (Wu et al., Energy & Environmental Science 2024), achieved 99.97 % mass recovery with identical efficiency after reuse—proof of concept for rapid, clean closed-loop recycling.
3. Creating a unified design framework.
The conceptual and quantitative design space for recyclable solar cells was formalized in “The Ideal Recyclable Solar Cell” (Peters & Brabec, Nature Reviews Chemistry 2025). This work introduces measurable parameters—intra-layer bonding, inter-layer bonding, bonding contrast, and locked-in entropy—to describe the trade-offs between performance, stability, and recyclability. It provides the first theoretical framework for assessing recyclability in photovoltaic materials and has since been adopted by other research groups in the field.
4. Prototyping recyclable module envelopes.
Modules built with the new edge-seal design were shown to be reusable: after separation, the glass package could be resealed, maintaining full moisture protection and mechanical integrity. Devices encapsulated in this reusable structure exhibited the same operational stability as conventional references, confirming the practical feasibility of circular module construction.
5. Economic and environmental validation.
Techno-economic models demonstrated that recycling substrates and solvents can reduce material costs by more than 60 % at both laboratory and industrial scale. Life-cycle assessments showed a 70 % reduction in energy payback time and greenhouse-gas emissions compared with conventional fabrication. These findings confirm that C2C design is not only environmentally beneficial but also economically attractive.
6. Outreach and recognition.
The project’s results have been featured in major media outlets, science podcasts, and a German television documentary on recycling. Two patents were filed, and the PI and team have been invited to multiple international conferences, including EU PVSEC, IEEE PVSC, and MRS, establishing C2C-PV as a reference initiative in circular photovoltaics.
C2C-PV advances photovoltaic research beyond the state of the art in four main areas:
1. From recycling to true cradle-to-cradle operation.
Previous recycling approaches focused on recovering a fraction of materials or down-cycling them into lower-value products. C2C-PV demonstrates for the first time that all functional layers of a perovskite solar cell can be recovered, purified, and reused without performance loss. This marks a transition from partial recycling to full circularity within the same technology.
2. Quantitative design principles for recyclability.
Before this project, recyclability in photovoltaics was discussed qualitatively. C2C-PV provides quantitative criteria—bonding strength, contrast, and entropy—to engineer interfaces that can be separated by design. These parameters bridge materials chemistry and device physics, offering a systematic methodology now used beyond the project’s immediate scope.
3. The concept of perpetual utility.
The project introduced a new sustainability metric that evaluates a photovoltaic system over multiple life cycles rather than a single operational period. This approach connects technological innovation with resource management, showing that circular design is a prerequisite for maintaining terawatt-scale production within global material limits.
4. Integration of techno-economic, environmental, and design models.
C2C-PV integrates life-cycle assessment, energy return on investment, and levelized cost of electricity into one multi-cycle model. This holistic perspective allows the optimization of efficiency, cost, and recyclability simultaneously—something no previous framework has achieved.
5. Broader impact and transferability.
The methodologies developed in C2C-PV—layer-by-layer separation, recyclable encapsulation, and multi-cycle modelling—extend beyond perovskite photovoltaics. They can be applied to other thin-film devices, batteries, and electronic materials. By linking green chemistry, interface science, and sustainable engineering, the project sets a blueprint for designing technologies that remain valuable after their first use.
1. From recycling to true cradle-to-cradle operation.
Previous recycling approaches focused on recovering a fraction of materials or down-cycling them into lower-value products. C2C-PV demonstrates for the first time that all functional layers of a perovskite solar cell can be recovered, purified, and reused without performance loss. This marks a transition from partial recycling to full circularity within the same technology.
2. Quantitative design principles for recyclability.
Before this project, recyclability in photovoltaics was discussed qualitatively. C2C-PV provides quantitative criteria—bonding strength, contrast, and entropy—to engineer interfaces that can be separated by design. These parameters bridge materials chemistry and device physics, offering a systematic methodology now used beyond the project’s immediate scope.
3. The concept of perpetual utility.
The project introduced a new sustainability metric that evaluates a photovoltaic system over multiple life cycles rather than a single operational period. This approach connects technological innovation with resource management, showing that circular design is a prerequisite for maintaining terawatt-scale production within global material limits.
4. Integration of techno-economic, environmental, and design models.
C2C-PV integrates life-cycle assessment, energy return on investment, and levelized cost of electricity into one multi-cycle model. This holistic perspective allows the optimization of efficiency, cost, and recyclability simultaneously—something no previous framework has achieved.
5. Broader impact and transferability.
The methodologies developed in C2C-PV—layer-by-layer separation, recyclable encapsulation, and multi-cycle modelling—extend beyond perovskite photovoltaics. They can be applied to other thin-film devices, batteries, and electronic materials. By linking green chemistry, interface science, and sustainable engineering, the project sets a blueprint for designing technologies that remain valuable after their first use.