Green antisolvent-mediators stabilize perovskites for efficient NiOx-based inverted solar cells with Voc approaching 1.2 V

Passivation of polycrystalline perovskite defects related to its surface, grain boundaries and buried interface is important to enhance the performance of perovskite photovoltaics. Here, a green and simple antisolvent-mediator contained ethylacetate and polymer polymethyl methacrylate, for the first time, is developed to stabilize the perovskite active layer. Such polymer-assisted mediators not only can facilitate perovskite crystal growth, but also passivate its interface and bulk defects. Under AM 1.5G illumination, the antisolvent-mediator processed NiOx-based inverted perovskite solar cells (PSCs) show a power conversion efficiency (PCE) of 22.21 % and a high open-circuit voltage (Voc) of 1.161 V. Besides, the devices further present a high PCE over 24 % under 0.6 suns, indicating efficient passivation of defects-induced non-radiative recombination. Importantly, a Voc approaching 1.20 V is obtained from 1-square-centimeter cells, which is the highest Voc in NiOx based inverted PSCs to the best of our knowledge. Compared to pristine cells, the antisolvent-mediators passivated cells without encapsulation retain 95 % of their initial values after 200 days. Furthermore, we can obtain a high Voc of 7.044 V for modules with 6 subcells connected in series.