The breakthrough shows that the technology works at a larger scale, not just in the lab, which is crucial for encouraging industry to take it up.
Each of the many individual cells forming the module is made of perovskite, a material of increasing interest to solar researchers as it can be made more easily and cheaply than silicon, the most commonly-used material for solar cells.
Perovskite solar cells have also proved to be highly efficient, with scores for power conversion efficiency (PCE) -- the amount of light striking a cell that it converts into electricity - as high as 22% on small lab samples.
The team work for the SPECIFIC Innovation and Knowledge Centre led by Swansea University. They used an existing type of cell, a Carbon Perovskite Solar Cell (C-PSC), made of different layers - titania, zirconia and carbon on top - which are all printable.
Though their efficiency is lower than other perovskite cell types, C-PSCs do not degrade as quickly, having already proved over 1 year’s stable operation under illumination.
The Swansea team's breakthrough comes from the optimization of the printing process on glass substrates as large as an A4 sheet of paper. They ensured the patterned layers were perfectly aligned through a method called registration, well-known in the printing industry.
The entire fabrication process was carried out in air, at ambient conditions, without requiring the costly high-vacuum processes which are needed for silicon manufacture.
The Swansea team achieved good performance for their modules:
- up to 6.3% power conversion efficiency (PCE) when assessed against the “1 sun” standard,
i.e. full simulated sunlight. This is world-leading for a C-PSC device of this size.
- 11% PCE at 200 lux, roughly equivalent to light levels in an average living room
- 18% PCE at 1000 lux, equating to light levels in an average supermarket.
The high efficiency ratings under indoor lighting conditions demonstrate that this technology has potential not only for energy generation outdoors but also for powering small electronic devices – such as smartphones and sensors – indoors.