Highly stable hole-conductor-free CH3NH3Pb(I1-xBrx)3 perovskite solar cells with carbon counter electrode

In this work, high stable perovskite solar cells (PSCs) based carbon counter electrode were fabricated in the air environment with 30% of humidity, in which the perovskite CH 3 NH 3 Pb(I 1- x Br x ) 3 were used as the absorber. We investigated the effect of the different Br-doping ( x  = 0.00, 0.10, 0.15, 0.20, 0.25, 0.30) on the devices performance and found that the appropriate amount of Br-doping could effectively improve crystallinity of the perovskite film and enhance the light absorption. When the doping-ration x was 0.25, the device exhibited the best performance with the efficiency of 9.99% with active area of 0.2 cm 2 under the irradiation of 100 mW/cm 2 air mass 1.5 global (AM1.5G) sunlight. By electrochemical impedance spectroscopy (EIS) measurement, we found that the introducing of Br − into the perovskite film could reduce the carrier recombination loss . Finally, the stability test of the PSCs was carried out and the result showed that the device still keep 96.23% of the initial efficiency after being stored in the air for 56 days (1344 h), which show an excellent stability.