A large-area hole-conductor-free perovskite solar cell based on a low-temperature carbon counter electrode

We demonstrate the application of low-temperature carbon counter electrode in fabricating large-area hole-conductor-free perovskite solar cell. A mesoscopic TiO2 film was deposited on a transparent conductive fluorine-doped tin oxide substrate by screen printing method. Then commercial conductive carbon slurry was printed to prepare the counter electrode at a temperature of 130 °C. The light absorber, CH3NH3PbI3, was formed instantly inside the pores of the entire TiO2/carbon layer upon single-step deposition of CH3NH3PbI3 precursor. The devices were characterized with XRD, SEM, and UV–vis absorption spectroscopy. As a result, an energy conversion efficiency of 3.3% with an active area of 2.25 cm2 was got under AM1.5G condition and there was no obvious decay during a testing period of 624 h. The carbon counter electrode has the features of low-cost and low-temperature preparation, giving it potential for application in the large-scale flexible fabrication of perovskite solar cells in the future