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SmArt Designed Full Printed Flexible RObust Efficient Organic HaLide PerOvskite solar cells

Periodic Reporting for period 2 - APOLO (SmArt Designed Full Printed Flexible RObust Efficient Organic HaLide PerOvskite solar cells)

Reporting period: 2019-10-01 to 2021-03-31

Conventional PV modules are limited in their design and have not been exploited fully in potential markets as buildings, textiles, automotive. Perovskite PV technology has an enormous potential to meet these needs without sacrificing high efficiency. The current main challenges of the technology lie in short lifetime, moderate efficiency with flexible substrates and higher production cost of high efficiency devices relative to the market-dominant silicon PV. The APOPLO consortium has been working since the beginning on surpass the aforementioned barriers for market deployment by the development of stable and reproducible high-efficient Perovskite Solar Cells (PSCs). The work is now focused on the use of scalable and low-cost processes in combination with materials and manufacturing methods that guarantee the protection of the environment. The project continues to work on the 4 pillars that define: obtain high-efficiency flexible devices through the development of new materials and the implementation of novel photonic structures, guarantee the stability of new concepts through the application of tests based on the PV standards, low temperature manufacturing using sustainable materials and processes and finally the integration of the new flexible APOLO modules in a prototype aimed at applications in Building Integrated Photovoltaics.
In the first phase of the project the developments carried out during the first 18 months gave rise to the first optimal set of materials and processes to achieve high efficiency devices and thinner active layers. After the complexion of the development phase, APOLO entered in a second period focused on transferring the first developments to flexible devices. In WP2, dedicated to advanced materials, internal materials used in the device have been developed with respect to device performance while external materials of liquid encapsulation and anti-soiling coating have been evaluated. As a complement, novel advanced characterization a technique based on potentiostatic photoluminescence imaging has been developed to investigate PET-based samples comprising different layers developed by the partners. In WP3 UNINOVA, FRAUNHOFER and UNITOV have focused on the development of combined optical and electrical programs to model the full opto-electronic response of the PSCs with and without Light Trapping (LT) structures. Also, the modelling of the modules has been used to determine the best layout to minimize losses to obtain 17% PCE modules that can be easily integrable in a BIPV final application. Fuelled by the materials in WP2 and models in WP3, WP4 continues with the up-scale APOLO devices on flexible substrates. Materials, formulations and devices have been shared and exchanged among partners to compared and validate results and to speed up APOLO progress. The improvement of the efficiency as well as the mechanical flexibility of PSCs has been pursued via the integration of light-management schemes in the devices indicated by the modelling studies of WP3. First devices has been manufactured using green formulations investigated. Metal-based PSCs were also fabricated, combining metal bottom electrodes and transparent top electrodes. Electrical designs has been combined with the aesthetical requirements for the integration of the flexible perovskite modules in a BIPV leading three different DEMO layouts. In WP5, on stability and recycling process, the encapsulation process has been adapted to the materials and flexible devices. On the other hand, the aging tests of the selected materials in WP2 and WP4 have started, including intrinsic aging test of rigid devices as well as light and damp heat aging (using encapsulated cells) as initial extrinsic evaluation. The mechanical testing protocol was also established and tested with flexible substrates. The feasibility of microwave recycling process for glass-based PSC has been proven and an additional solvent dissolution recycling process was specifically developed for flexible (PET-based) PSC. Finally, In WP6 dedicated to the environmental and economical assessment LEITAT had refined the life cycle inventory data and the impact results relating to final APOLO demos. APOLO PSCs modules manufacturing procedures has been analysed step by step allowing the first calculations of LCOE of APOLO modules including both, concrete and real data and reasonable assumption for missing data. Dissemination, communication and exploitation activities has been performed witting WP7 in line with the different technical developments.
APOLO achieved a PCE of 22.59% (rigid devices) employing passivation layers and tuned perovskite, value that was significantly improved from it was reported in the first period (20.79 %). The optimization of the HTMs based on benzodipyrrole (BDP) resulted in a PCE of 18.23% that was improved from what was reported previously (16.9%), but still inferior to that using commercial Spiro-MeOTAD (20.23%). Thus, the consortium decided to select an alternative HTM towards high efficiency and stable devices, obtaining up to 16% PCE on flexible PSCs. Exploring alternative approach for large area deposition of the perovskite, flexible cells were fabricated using low temperature processing reaching 19.2% PCE (0.33 cm²). Promising mixture of a green solvents were tested for the perovskite layers on complete flexible devices. In addition to the polymeric-based devices, flexible cells on metal foils have been fabricated and achieved 2.4% PCE . A light-management scheme allowed up to 19.9% enhancement in the photocurrent of a first batch of photonic-structured PSCs, but even better performances are anticipated for subsequent batches. Great efforts have been made in modelling the electrical losses of modules that also meet the integration requirements in the final demonstrators. Blade coating of the perovskite film led to 18% PCE on modules on glass substrates (10 cm2) with geometrical fill factor of 93%. On the other hand, automated spray coating process to deposit Electron Transport layers, transferred to flexible PET substrates, and an optimization of the laser processing, led to flexible modules delivering an average PCE of 10.5% on 16.84 cm2 (12% PCE for the best module) and an average PCE of 9.9% on 21.84 cm2 (10.7% PCE for the best module). Considering the stability in damp heat aging conditions of flexible cells encapsulated with liquid adhesives, no losses were identified after 750h using glass encapsulation + commercial adhesives while 85% of initial performances was maintained after 800h in storage (Dark/Air) using flexible encapsulation + APOLO glue. The cost to manufacture a flexible perovskite solar module has been modelled taking in account state-of-the-art and APOLO present scenario. The cost range can be set in 1.64€/Wp to 1.41€/Wp for flexible modules manufactured in factory sizes ranging from 1 MW/year to 200MW/year.
Flexible module APOLO