Light stability tests of CH3NH3PbI3 perovskite solar cells using porous carbon counter electrodes

The CH3NH3PbI3 perovskite solar cells have been fabricated using three-porous-layered electrodes as, hglass/F-doped tin oxide (FTO)/dense TiO2/porous TiO2-perovskite/porous ZrO2-perovskite/porous carbon-perovskitei for light stability tests. Without encapsulation in air, the CH3NH3PbI3 perovskite solar cells maintained 80% of photoenergy conversion efficiency from the initial value up to 100 h under light irradiation (AM 1.5, 100 mW cm(-2)). Considering the color variation of the CH3NH3PbI3 perovskite layer, the significant improvement of light stability is due to the moisture-blocking effect of the porous carbon back electrodes. The strong interaction between carbon and CH3NH3PbI3 perovskite was proposed by the measurements of X-ray photoelectron spectroscopy and X-ray diffraction of the porous carbon-perovskite layers.