Perovskite PV has shown great promise in terms of device efficiency, but also in terms of scalability through solution process manufacturing. Efforts to scale perovskites have been conducted using printable mesoporous scaffolds and roll-to-roll (R2R) coating of flexible substrates.
However, fully R2R-coated devices have not been demonstrated to date due to the lack of a compatible solution-processable back electrode; instead, high-value evaporated metal contacts are used as post-processing.
Engineers at Swansea University’s SPECIFIC Knowledge and Innovation Center have developed a scalable, low-cost carbon ink formulation capable of unlocking the potential of large-scale cell manufacturing for the first time perovskite solar panels.
Researchers used slot matrix coating in a roll-to-roll (R2R) process to develop a “fully printable” perovskite photovoltaic (PV) system. They were looking for an alternative to the gold electrode which is often applied via an expensive and slow evaporation process after the device has been printed.
The key was finding the right mixture of solvents that would dry into a film without dissolving the underlying layer. X-ray diffraction analysis demonstrated that carbon electrode ink is capable of this when formulated with an orthogonal solvent system. This innovative coating can be applied continuously and is compatible with underlying low temperature and high speed coatings.
David Beynon, SPECIFIC Principal Investigator.
The new device fully coated with R2R was printed on a 20 m long flexible substrate. In laboratory tests, devices with carbon electrodes provided photovoltaic performance similar to that of conventional evaporated gold electrodes. Specifically, the results showed that small-scale device efficiencies of 13–14% are achieved, matching the performance of the evaporated gold electrode device.
Additional benefits include better performance at higher temperatures and greater long-term stability. Additionally, this fully encapsulated prototype R2R perovskite achieved a stabilized power conversion efficiency greater than 10% (10.8), with unencapsulated long-term stability retaining 84% of its original efficiency over 1000 hours.
For us at Swansea University, the next challenge in printed photovoltaics is to show people that it works. To do that, we need to start making something that actually looks like a solar panel. Then we can install them in buildings and see how close we are to delivering on the promise of making green renewables in the UK.