Enhancing hole-conductor-free, printable mesoscopic perovskite solar cells through post-fabrication treatment via electrophilic reaction

Hole-conductor-free printable mesoscopic perovskite solar cells, fabricated by infiltrating perovskite into the preprinted porous TiO2/ZrO2/carbon triple-layer scaffold, offer an approach for the industrial production of photovoltaic panels. Here we introduce a reactive post-processing strategy using hexamethylene diisocyanate to enable efficient collection and transport of holes from the perovskite to the carbon electrode. Hexamethylene diisocyanate reacts with excess organic cations at the perovskite crystal terminations through an electrophilic reaction and reconstructs the grain boundaries and the back interface. The treatment passivates defects, facilitates hole transport in perovskite and enhances hole transfer from the perovskite to the carbon electrode. We achieve an efficiency of 23.2% for the laboratory-size device with an aperture area of 0.1 cm2 and 19.4% for the minimodule with an aperture area of 57.3 cm2. The devices retain 95% of their initial efficiency after 900 h of continuous operation at the maximum power point under elevated temperatures of 55 ± 5 °C. Printable mesoscopic perovskite solar cells are a promising device design, yet their efficiency is limited by charge collection. Ma et al. use hexamethylene diisocyanate to eliminate unreacted organic cations at grain boundaries, enhancing hole collection.