Ultra-low dark current and high sensitivity lead-free perovskite–like photodetector realized by anti-solvent optimization Cs3Bi2I9 amorphous film

Compared with lead halide perovskite, bismuth-based perovskite has lower toxicity and air stability, demonstrating enormous potential for application, among them, Cs₃Bi₂I₉ materials has been researched as an alternative to lead-based perovskite for application of optoelectronic devices. It is crucial for the realization of high-performance photodetectors which need high-quality perovskite thin films. Here, we prepared a lead-free, all-inorganic, Cs₃Bi₂I₉ perovskite-like amorphous films by spin coating method, and diethyl ether was added as an anti-solvent at different times of spin-coating. The results show that the homogeneous and dense Cs₃Bi₂I₉ amorphous films can be obtained by adding anti-solvent at 14 s. Furthermore, Cs₃Bi₂I₉ perovskite-like UV photodetector achieved extremely low dark current around ∼ pA range, high sensitivity of 1.10 × 10⁴ was fabricated. Our research shows that the preparation of Cs₃Bi₂I₉ amorphous films by the simple antisolvent-assisted spin-coating method are very promising for optoelectronic device.