Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - CHEOPS (Production technology to achieve low Cost and Highly Efficient phOtovoltaic Perovskite Solar cells)

Teaser

The aim of CHEOPS was to develop very low-cost but highly performing photovoltaic (PV) devices based on the emerging perovskite (PK) technology. At lab scale (20%. But only few attempts at upscaling had been made, yielding significantly reduced efficiencies 14% stable for...

Summary

The aim of CHEOPS was to develop very low-cost but highly performing photovoltaic (PV) devices based on the emerging perovskite (PK) technology. At lab scale (<0.5cm2), PK energy conversion was rapidly advanced to efficiencies >20%. But only few attempts at upscaling had been made, yielding significantly reduced efficiencies <9% on aperture area. In addition, the very question about material stability and reliable measurement procedures were still debated. CHEOPS set out to scale up the lab results to single junction modules manufactured in a preproduction environment while maintaining high efficiencies (>14% stable for aperture area in modules >15x15cm2). This was aimed at demonstrating the potential of PK as a very low-cost technology (target <0.3 €/Wp) well suited for building-integrated PV. In parallel, CHEOPS targeted the development of materials and processes to achieve very high efficiency (>29% on 2x2 cm2 cells) at low cost (target <0.4€/Wp) using a tandem configuration with a crystalline silicon heterojunction cell. CHEOPS also planned to perform a sustainability assessment from a lifecycle perspective to anticipate potential risks for the technology (including business, technological, environmental, social & political risks). CHEOPS was to establish a quantified future development roadmap as well as protocols for stability testing and for reliable measurements. By fulfilling all these goals, CHEOPS aimed at demonstrating that the emerging perovskite based PV technology is indeed a future solution to support large development of renewable electricity source towards a decarbonised society.

Work performed

In terms of developments towards the upscaling of high efficiency single junction device, CHEOPS partners could demonstrate efficiencies among the highest reported so far on large scale devices up to 45 cm2, reaching 13.4% steady state efficiency while steady state efficiency of 14% has been reported on aperture area of 13.7 cm2. In addition, the deposition of perovskite on larger area has also been demonstrated via inkjet printing. However, first devices using such processes demonstrated lower efficiencies probably related to the presence of point defects when printing the material on large area. This should be the point of focus for future developments of large scale perovskite deposition processes.

In terms of measurement methodology the partners have set standards in order to relevantly compare their results. These stress the fact that IV measurements must be carried out with MPP after 5 min of stabilisation or that the presented results must be a mean of at least 4 different samples deposited in the same conditions in order to ensure a sufficient statistical significance. On the side of device stability, several encapsulation techniques have been validated that allow preserving the device initial efficiency during the encapsulation process itself.

Regarding the evaluation of the potential technology environmental impact, a set of typical structures (single, tandem) using different materials deposited with various techniques has been established with as much information as possible on their deposition conditions (e.g. type of solvents, typical thickness, water consumption etc.). In addition, a series of tests to evaluate possible environmental impact in case of module breakage has been performed to investigate release of potentially harmful substances into the air, water and ground.

Regarding tandem junction developments, CHEOPS partners have been able to demonstrate the upscaling of tandem devices to areas greatly exceeding the 2x2 cm2 initially requested. Thereby they provide a clear pathway to high efficiency, large area tandem devices. Regarding power conversion efficiencies, while still behind the requested 29%, CHEOPS has set the mark with the highest certified, peer-reviewed result at 25.2% on textured wafers and another internally measured 25.4% on flat wafers. It is worth noting here that the absolute record to date is held by another CHEOPS partner, Oxford PV, at 28%, albeit outside of the CHEOPS project.

Regarding the dissemination and exploitation activities, the results of CHEOPS have been communicated to the wider public via its website and newsletter while an industrial advisory board was implemented to receive advice and inform potentially interested stakeholders about the project progresses. In addition, the results of CHEOPS have been diffused in the scientific community via scientific publication in renowned journals or via the participation to several international conferences. Eventually, CHEOPS also organised a European perovskite cluster event gathering all EU funded projects active in the field of perovskite PV.

Regarding the exploitation of the developed technologies, and beside the direct support to the activities of consortium members, several projects have been set up based on the acquired know-how. These range from direct bilateral collaboration with industrial partners (outside the CHEOPS consortium) to further upscale the technology to other collaborative projects at the national or international level, including other H2020 projects such as PERTPV (Grant agreement No. 763977).

Final results

In conclusion, CHEOPS partners established themselves at the forefront of PK/Si development worldwide, setting the pace towards very high efficiency devices. However, even though CHEOPS clearly demonstrated that 30% devices are within reach, this is bound to happen over a timescale longer than that of the CHEOPS project.
Regarding the broader socio-economic analysis of the technology, it has been shown that its total health and environmental benefit could amount to about €220 M€ per year at the European scale if half of the newly installed photovoltaic installations each year were based on PK technologies rather than c-Si. Balancing health and environmental benefits with the issue of PK cells’ Pb content results in a trade-off largely in favour of a development of PK technologies. Nevertheless, our work has shown that great vigilance must be expected from industry to curb lead emissions to the environment.

Website & more info

More info: http://www.cheops-project.eu.