Perovskite solar cells (PSCs) with power-conversion efficiencies comparable to established technologies hold huge promise for becoming the future photovoltaic technology, also given their versatility, low-cost and energy-efficient fabrication processes1. However, PSCs are not stable under moderate reverse bias2–4, an unavoidable situation under real-world operation, for instance, caused by partial shading of a module or installation with PSCs connected in series. Approaches to address this issue have focused on engineering the device architecture to enhance the breakdown voltage and mitigate the detrimental effects of reverse bias2,5,6. Here we present a completely different approach that fully solves the reverse-bias issue. With our Memsol, we developed a new concept of a solar cell with an integrated memristor, which protects the solar cell and simultaneously works as a bypass element. The memristor is realized by area-selective deposition of an additional metal–insulator stack and shares the perovskite and electrodes with the solar-cell part. Reverse-bias and shading tests show that the Memsol remains stable and automatically toggles between a low-resistance bypass state and full-efficiency solar-cell operation, dependent on the illumination and bias conditions. We anticipate that our Memsol concept, which we demonstrated on a nine-cell string in the lab, will be implemented in large-scale modules, accelerating their commercialization and potentially making external bypass diodes unnecessary.
