TiO_2 nanotube/TiO_2 nanoparticle hybrid photoanode for hole-conductor-free perovskite solar cells based on carbon counter electrodes

In this work, TiO2 nanotubes were assembled in the hole-conductor-free, carbon counter electrode-based (CH3NH3)PbI3 perovskite solar cells based on the TiO2 nanotube/TiO2 nanoparticle hybrid photoanode under ambient conditions, on which TiO2 nanotubes were uniformly embedded in the hybrid photoanode, and their structure was not affected by the assembly process. Compared with cells based on TiO2 nanoparticles, the cells exhibited a power conversion efficiency of 9.16% that was improved by 40% under similar conditions. The optimized device structure provided effective transport pathways for carrier and carrier recombination was effectively suppressed. In addition, the TiO2 hybrid photoanode ensured efficient light trapping by the sensitizers, leading to an increase in the number of photogenerated carriers.