The tailored inner space of TiO2 electrodes via a 30 second wet etching process: high efficiency solid-state perovskite solar cells.

We fabricated a perovskite solar cell with enhanced device efficiency based on the tailored inner space of the TiO2 electrode by utilizing a very short chemical etching process. It was found that the mesoporous TiO2 photoanode treated with a HF solution exhibited remarkably enhanced power conversion efficiencies under simulated AM 1.5G one sun illumination. The controlled inner space and morphology of the etched TiO2 electrode provide an optimized space for perovskite sensitizers and infiltration of a hole transport layer without sacrificing its original electron transport ability, which resulted in higher JSC, FF and VOC values. This simple platform provides new opportunities for tailoring the microstructure of the TiO2 electrode and has great potential in various optoelectronic devices utilizing metal oxide nanostructures.