Community Research and Development Information Service - CORDIS

Final Report Summary - PBFREEPEROVSKITES (Pb-Free Perovskites for Efficient All-Solid-State Hybrid Solar Cells)

Hybrid lead halide perovskite absorbers offer an extremely promising solution to solar energy conversion, in line with the European Union’s 2020 renewable energy targets. This family of materials can be processed from solution utilizing common techniques and equipment developed by the printing industry, achieving power conversion efficiencies on par with the silicon industry. However, the state-of-the-art perovskite developed uses lead, which is highly toxic and water soluble. This poses a serious environmental threat and a serious deterrent to the commercial development of this technology. Furthermore, in the usual processing scheme, toxic solvents are used, which in combination with the carcinogenic lead salts employed make the production of these devices rather hazardous. Thus, this project sought to address these issues through the development of a new approach to form lead-free perovskite films from non-toxic solvents.

Main results:
The fellow has developed a new deposition method based on a two-step approach, where firstly the lead precursor is deposited on the solar cell substrate and the rest of the components are added into the structure in a second step via immersion of the substrate in a solution. This approach proved to be extremely versatile, giving access to a very large variety of highly pure and homogeneous perovskite thin films. The fellow immediately showed higher performance for devices prepared with this new approach as compared to other approaches reported at the time.

Aided by this new approach, the fellow explored many different perovskite structures, leading to over 15 publications and 3 patent applications. Of particular relevance, the fellow used the structures developed during this part of the project to prepare the first perovskite light-emitting diodes in an international collaboration with the University of Cambridge. This showed that the newly discovered family of materials can also be used for efficient lighting applications, opening a completely new field of research.

Finally, the fellow developed lead-free alternative perovskite materials based on Tin. Furthermore, the fellow developed a deposition protocol which foregoes the hazardous DMF solvent for relatively safe dioxane and methanol solvents. This development can also potentially be applied for other perovskite materials, perhaps leading to safer production conditions in future fabrication plants.

Socioeconomic impact:
The development of novel lead-free structures is a crucial event in the roadmap to commercial implementation of perovskite solar cells. While at present the developed materials still suffer from stability and performance issues, the exploratory results of the project can be taken as a stepping stone in the search for safer materials for our solar parks. The fellow has communicated his results with the leading start-up in the area, Oxford PV, and future developments along these lines are expected.

On the other hand, the development of the new perovskite-based LEDs marks a major landmark in the field. The developed perovskite materials re-emit nearly 90 % of absorbed photons as photoluminescence, which when translated into electrical devices means that for every electron put into the material, potentially 0.90 photons will come out; an efficiency found only in our state-of-the-art commercial devices. As the materials can in effect be printed, this development has the potential to revolutionise the lighting industry. Licencing of the LED application is already under way via Cambridge Enterprise and fabrication of first prototypes for commercial products has commenced.

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