Perovskite solar cells with enhanced stability and applicability

Projektinformationen

VALHALLA

ID Finanzhilfevereinbarung: 101082176

DOI

10.3030/101082176

Projekt abgeschlossen

EK-Unterschriftsdatum 20 September 2022

Startdatum 1 Januar 2023

Enddatum 31 Dezember 2025

Finanziert unter

• Climate, Energy and Mobility

Gesamtkosten

€ 3 877 396,50

EU-Beitrag

€ 3 877 396,50

Koordiniert durch

UNIVERSITAT DE VALENCIA
Spain

Periodic Reporting for period 2 - VALHALLA (Perovskite solar cells with enhanced stability and applicability)

Berichtszeitraum: 2024-07-01 bis 2025-12-31

Zusammenfassung vom Kontext und den Gesamtzielen des Projekts

VALHALLA aims to accelerate Europe’s transition to clean energy by developing perovskite solar cells and modules with power conversion efficiencies above 26 % (modules > 23 %) and extrapolated operational lifetime > 25 years, following an eco-design approach: employing harmful-solvent-free perovskite deposition, optimized use of materials, circularity, recyclability, scalable and low-cost manufacturing processes, to create a viable economic pathway for the European commercialization of this sustainable technology.
To do so, VALHALLA is developing
- efficient perovskite (PVSK) absorbers made with methods avoiding the use of solvents, stable towards light, heat.
- Integrate these absorbers in single junction solar cells, opaque and semitransparent, using rigid and flexible substrates and with indium free electrodes.
- rigid and flexible encapsulation methods
- ·outdoor and indoor test facilities.
- accelerated lifetime test equipment will be developed using input from the outdoor test results on VALHALLA samples.
- Characterize pristine and aged devices and films with a wide range of techniques.
- Use molecular and physical modelling to identify degradation pathways and measures to overcome them.
VALHALLA will also demonstrate
·the economic viability, environmental harmlessness and social acceptance of the technology with the calculation of its lifecycle costing (LCC), environmental and social lifecycle analysis (LCA).
VALHALLA is a multidisciplinary team consisting of 12 partners from 8 European countries, 2 associate member countries and 1 widening country; 3 industrial partners & 9 Research & Technology organizations.

Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse

In WP1, partners developed perovskite semiconductors using co-sublimation and sequential sublimation of the precursors with bandgaps ranging from 1.3 to 2.0 eV. In contrast to what is generally observed for solution processable perovskites, we found that when exposed to heat and light perovskites containing formamidum and methylammonium were more stable than those containing cesium and formamidium. Suitable charge extraction layers were found and developed that match the valence and conduction bands of the perovskites. An electron transport molecule capable of self assembling on a suitable surface was developed for which a patent was applied. We identified I2 loss as one of the photodegradation mechanism of lead based perovskites.

In WP2, partners developed all vacuum deposited single junction solar cells with power conversion efficiency reaching 23.3 % a record value as far as we know. Flexible solar cells on very thin polyetherketone was developed with a power conversion efficiency of 22 %. Semitransparent solar cells with an average visible transmittance of 50 % with a power conversion efficiency of 9.6 % were developed. We prepared semitransparent solar cells with transparent conducting electrode based on aluminium doped zinc oxide deposited using pulsed laser deposition. Detailed balance limit calculation allowed to identify limiting factors of perovskite solar cells with several bandgaps. And a new method based on impedance spectroscopy allows to determine ionic mobility in perovskite devices.

In WP3 perovskite deposition using co- and sequential sublimation was achieved at areas over 100 cm2. Modules using these large area substrates were prepared using laser scribing to generate multiple cells placed in series. An effective encapsulation based on glass-glass was developed for rigid cells. This, encapsulation method lead to negligible lead leaching even in broken modules/cells

In WP4, outdoor monitoring setups were installed capable of tracking irradiance, temperature, power output simultaneously. Outdoor stability of vacuum and hybrid processed Solar Cells > 12 months with only 20 % decay.
Using SIMsalabim and Bayesian Optimization Tool BOAR we identified that the HTL/perovskite interface and increased trap density were the main causes for the efficiency loss. The degradation mechanism of lead iodide perovskite in presence of O2/H2O has been studied by DFT simulations. H2O preferentially removes the organic FAI moiety from the surface and O2 leads to the formation of periodates which activate the formation of PbI2 vacancies that lead to the degradation of the material. The use of molecular binder, e.g. amines, sulfonium molecules, and hydrophobic large cations, e.g. EDAI2, as passivants increases the long term stability and efficiency of the perovskites.

In WP5, the most used perovskite solar cell stacks were identified and the materials used in these stacks were compared on global warming potential. Due to a low intrinsic value, recycling perovskite PV is technically possible but economically irrational.

Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)

State-of-the-art perovskite solar cells typically employ solution-processed perovskite layers that use toxic solvents In-based TCO layers. In VALHALLA we have developed high quality perovskite absorbers with a wide range of bandgaps. When integrated into single junction solar cells power conversion efficiencies in excess of 20 % were achieved including a record value of 23.3 for a completely vacuum deposited device stack.
We found that when exposed to heat (85 degrees C) and light (1 sun) perovskite containing formamidum and methylammonium were more stable than those containing cesium and formamidium. Best stability achieved with a sequential deposited device T90 > 1000 hours (85°C, 1 sun)
Semitransparent solar cells with an average visible transmittance of 50 % with a power conversion efficiency of 9.6 % were developed.
A commercial equipment was developed to study accelerated aging of perovskite solar cells.