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 J_SC, FF and V_OC 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.