(C6H5NH3)BiI4: a lead-free perovskite with >330 days humidity stability for optoelectronic applications

A key challenge in the eco-friendly optoelectronic materials field is to find highly stable and nontoxic perovskite materials. Here, we report the optoelectronic properties and stability of the (C6H5NH3)BiI4 perovskite material. Using an eco-friendly gas pump treatment technique, a dense and pinhole-free (C6H5NH3)BiI4 film was fabricated. Remarkably, a large-area (>20 cm(2)) Bi-based perovskite film was obtained, which is the largest Bi-based perovskite film ever reported. Besides, the (C6H5NH3)BiI4 perovskite exhibits good solubility in ethanol, which is a safe and eco-friendly solvent. Thermogravimetric analysis results show the beginning of weight loss at similar to 184 degrees C, suggesting excellent heat stability of this material. Most importantly, the (C6H5NH3)BiI4 material can tolerate continuous moisture exposure for 334 days in ambient air owing to the presence of a hydrophobic organic chain. To the best of our knowledge, this is the longest moisture stability reported for lead-free perovskite materials so far. This work paves the way for realizing highly stable and nontoxic perovskite materials for potential optoelectronic applications.