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Efficient Structures and Processes for Reliable Perovskite Solar Modules

Periodic Reporting for period 1 - ESPResSo (Efficient Structures and Processes for Reliable Perovskite Solar Modules)

Reporting period: 2018-04-01 to 2019-09-30

With its low-cost materials and low temperature deposition processes, perovskite-based solar cell technology has the potential to take its place in the thin-film photovoltaics (PV) market. Perovskite solar cells have already demonstrated high efficiencies that rival those of established mainstream thin-film PV technologies like copper-indium-gallium-selenide (CIGS) and cadmium-telluride (CdTe). The challenge is now to transfer the unprecedented progress that the perovskite PV cell technology has made in recent years from its cell level into a scalable, stable, low-cost technology on module level.
The ESPResSo team targets alternative cost effective materials, novel cell concepts and architectures, and advanced processing know-how and equipment to overcome the current limitations of this technology. The consortium aims to bring the cell performance close to its theoretical limit by demonstrating cell efficiency of more than 24% (on 1cm²) and less than 10% degradation in cell efficiency following thermal stress at 85°C, 85% RH for over 1000h. Scale up activities utilising solution processed slot-die coating and laser processing will additionally deliver modules with more than 17% efficiency showing long-term (>20 years) reliable performance as deduced from IEC-compliant test conditions.
The ESPResSo team also envisions integrating modules in façade elements demonstrating a levelised cost of electricity (LCoE) of ≤ 0.05€/kWh. Prototyping advanced, arbitrary-shaped architectures with specific materials and process combinations will emphasize that new highly innovative applications like on flexible substrates or with high semi-transparency are well accessible in the mid- to longer-term with this very promising thin-film PV technology
A variety of perovskite compositions and architectures has been evaluated. This has resulted in the best power conversion efficiency (PCE) of 23.8%, though still on cell area smaller than 1cm2. It is anticipated that using optical management techniques like anti-reflection coating, the generated photocurrent can be further improved from 25mA/cm2 to over 26mA/cm2.
Therefore, in the second project period it will be aimed for to combine the optimal properties of the perovskite compositions and transport layers in one highly performing device architecture, enabling to achieve PCE > 24%.
Similarly, a variety of devices, both cells and mini-modules, have been evaluated under long term stress factors like temperature, light and humidity. Modifications on the transport layers, or use of metal-free electrodes, has resulted in stable performance beyond 600hrs and even up to 1000hrs under elevated temperature of 60 or 85C. To reach the similar target of less than 10% reduction in efficiency under 85% relative humidity for 1000hrs, it is clearly figured out by now that high impermeable packaging is required to reach that. The development of such packaging by several techniques is ongoing.
Modules on flexible substrates have been fabricated already successfully. Use of inkjet printing has resulted in devices with efficiency up to 16%, and loss analysis has identified how the module design on flexible substrates can be adapted to minimize the reduction in performance compared to its counterparts on glass.
Gradual development of large area deposition processes including blade and slot die coating for the perovskite photo-active layer as well as some transport layers and electrode materials has resulted in full modules processed up to 10x10cm2 and even first versions up to 30x30cm2. The former ones have achieved efficiency over 14%, the latter ones lag a bit behind still on the efficiency value.
For the novel One-Step Interconnection (OSI) process first and even improved generations of both insulator and conductive inks have been evaluated on their chemical compatibility with the solar cell materials and their dispensing and printing ability. Proof of concept has been demonstrated in first trials on fully processed modules, whereby active area efficiency has been achieved comparable to (mini-) modules with the conventional interconnection scheme.
The fabrication of a building integration demonstrator has been initiated already. The design, assembly process and materials selection has been discussed and dummy samples have been exchanged between involved partners. The module process flow and its tool, material and input energy requirements have already been identified. This forms the basis for the cost calculation, which then complemented with performance (efficiency and lifetime) data to be gathered in the next project period will result in getting the set targets of identifying the LCoE (levelized cost of electricity) of this building integrated scenario.
A thorough analysis and data library has been set up on materials, processes and device architectures developed by the partners in this consortium, complemented with literature research, to perform the life-cycle assessment taking toxicological, ecological and eco-profile impact analysis onto account. This will form the basis also to quantify the environmental product footprint for the building integrated demonstrator to be realized.
Finally, market analysis and definition of USPs (Unique Selling Propositions) for selected use cases of perovskite PV technology has also been initiated. Road mapping for market introduction is thereby already done mostly based on technological aspects. This will be further balanced with the environmental product footprint analysis mentioned above to overcome potential roadblocks for full acceptance by the general public, policy makers and other stakeholders.
The high cell performance, large area module processing and improved stability as achieved already by this consortium is competitive with current state-of-the-art. Further increased performance is targeted for the second project period making it very reasonable to progress clearly beyond the state-of-art on these different aspects.
The detailed life cycle and toxicity analysis, eco-footprint as well as cost calculations are hardly reported in literature up to the level anticipated in this project. The building integration demonstrator as well-developed use case is also a result not yet found back in literature.
With this progress, the project will substantially reduce the technological risks and thus de-risking future investments in a broad set of activities like building integration photovoltaics, but also flexible, customized and even tandem applications.
Covering also the life cycle and ecological aspects, the project will enable substantial reduction of environmental impact, by using more environmentally friendly materials, minimising material usage and by significantly extending the module lifetime overall a higher ratio of energy generated over energy used in production.
With several SMEs as partner in the consortium, the project collaboration enables them to build jointly a future technology base in Europe, ranging from materials, tools, thin-film modules up to final application products.
As such the results obtained will have a positive impact on CO2 reduction - supporting the ambitious European goals -, novel employment in renewable energy activities, and thus contributing to solving the global climate and energy challenges.
How ESPResSo will progress the technology development of perovskite photovoltaics