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Perovskite Solar Cells with Carbon-Graphite Back Electrode

With perovskite solar cells, which have a carbon-graphite layer as the back electrode, the longest operating times of 9,000h - 10,000h reported for perovskite solar cells in the literature were achieved. The decisive factor here is the lack of metal ions diffusing from the electrode through the solar cell. In addition, not only the material costs are lower in perspective, but also the overall manufacturing costs due to the avoidance of vacuum process costs, as well as the CO2-equivalent footprint of production. However, these results have so far been achieved with graphite pastes that have to be sintered at high temperatures (HT), which limits the flexibility in solar cell production and design and thus the potential for optimizing efficiency. Recently, optimized so-called low-temperature carbon-graphite (LT-C) pastes have become available that can be used instead of metal electrodes in potentially high-efficiency solar cell configurations. These LT-C pastes have the potential to combine the best of both worlds and enable fully printed perovskite solar cells with the highest efficiencies and operational stability. So far, however, this potential has not been fully exploited. For this reason, we are trying to understand the basic processes in such LT-C solar cells and to optimize their production.