Scaled up with Almost No Losses

Scaling up the surface area from cell to module level without sacrificing efficiency is a key challenge associated with the development of promising perovskites photovoltaics technology. Karlsruhe Institute of Technology (KIT) has now announced an important breakthrough in this regard. The Germany-based research center proposed the use of laser based monolithic integration for establishing series connection in combination with vacuum processing of all layers, which has enabled production of perovskite solar modules "almost without any losses." The resultaing solar module with a surface area of 4 cm² reached a power conversion efficiency of 18%, which according to KIT is a world record for vacuum-processed perovskite solar modules, and 16.6% on 50 cm².
Perovskite solar cells are thin-film solar substates, which are divided into small cell strips by separating individual layer by means of monolithic structuring to establish series connection. These layers of Perovskite solar modules formed thorough evaporation in a vacuum have so far suffered significant losses of efficiency due to the scaling up process.
The reasons for the losses are: 1. the larger the surfaces, the more difficult the separation of the individual solar cell layers; and 2. the areas between the cell strips do not contribute to power generation, thus regarded as dead surfaces.
The KIT team has now succeeded in minimizing the influence of both the loss mechanisms by evaporating all layers of the solar modules in a vacuum.
"Great advantages of the separation from the vacuum with regard to the production of efficient solar modules are the simple controllability of the processes, the low number of process parameters and in particular the independence of the separation mechanism from the coating surface," explains Tobias Abzieher, who is leading the development from the vacuum of isolated perovskite solar cells at KIT's Lighting Engineering Institute (LTI).
The LTI researchers further combined this innovative process with high-precision laser structuring. This is the first time to produce a large-scale perovskite solar module with almost no loss of scaling – an important step from the laboratory to the industry, the research center underscores, according to the researchers. "Despite the increase of the component area by a factor of more than 500, there is almost no loss of efficiency," said David Ritzer of LTI, who developed the high-precision laser circuit of the device.
The scientists presented their findings at this year's Spring Meeting of the Materials Research Society (MRS). The research team focused on optimizing the pure solar cell layer stack as well as reducing the dead areas to improve the performance further. They note that the production of perovskite solar modules with efficiencies of well over 20% is a timely goal even on larger surfaces.
Researchers around the world are working on scaling up sizes as they produce mini modules from perovskite cells. In early April, Jiangsu, China based solar technology company Wuxi Utmost Light Technology Co Ltd (UtmoLight) has announced what it touted as a 'new world record' of reaching 20.5% power conversion efficiency for a perovskite solar module.Confirming that the efficiency was certified by Japan Electrical Safety & Environment Technology Laboratories (JET), UtmoLight said it achieved this efficiency for its mini module with a designated area of 63.98 cm². It claimed this was the highest record generated by perovskite solar modules in the world (see 20.5% 'Record' Efficiency For Perovskite Module).