A comparative study of planar and mesoporous perovskite solar cells with printable carbon electrodes

Devices with printable carbon electrodes are promising directions for the commercialization of perovskite solar cells. Most of perovskite solar cells employ mesoporous device structures when using printable carbon as the counter electrodes. Here, we carry a comparative study of planar and mesoporous perovskite solar cells with carbon electrodes. The device efficiency is significantly reduced from 11.37% to 5.27% when the mesoporous TiO2 film is removed from the device structure. Compared with the planar device, smaller carrier transport resistance and bigger carrier recombination resistance are demonstrated for the mesoporous device. Results suggest that the presence of mesoporous TiO2 enables an efficient electron extraction from the perovskite absorber, which remits the serious carrier recombination in the hole transport layer free device due to the hole accumulation. Therefore, the electron extraction efficiency is crucial in these hole transport layer free devices with carbon electrodes. This study helps to develop further optimization of low temperature carbon-based perovskite solar cells for higher reproducibility and higher device performance.