Completely Solvent-free Protocols to Access Phase-Pure, Metastable Metal Halide Perovskites and Functional Photodetectors from the Precursor Salts

• Published in: iScience 2019-06, Vol.16, p.312-325
• Main Authors: Hong, Zonghan, Tan, Davin, John, Rohit Abraham, Tay, Yong Kang Eugene, Ho, Yan King Terence, Zhao, Xin, Sum, Tze Chien, Mathews, Nripan, García, Felipe, Soo, Han Sen
• Format: Article
• Language: English
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2019.05.042

Mechanochemistry is a green, solid-state, re-emerging synthetic technique that can rapidly form complex molecules and materials without exogenous heat or solvent(s). Herein, we report the application of solvent-free mechanochemical ball milling for the synthesis of metal halide perovskites, to overcome problems with solution-based syntheses. We prepared phase-pure, air-sensitive CsSnX (X = I, Br, Cl) and its mixed halide perovskites by mechanochemistry for the first time by reactions between cesium and tin(II) halides. Notably, we report the sole examples where metastable, high-temperature phases like cubic CsSnCl , cubic CsPbI , and trigonal FAPbI were accessible at ambient temperatures and pressures without post-synthetic processing. The perovskites can be prepared up to "kilogram scales." Lead-free, all-inorganic photodetector devices were fabricated using the mechanosynthesized CsSnBr Cl under solvent-free conditions and showed 10-fold differences between on-off currents. We highlight an essentially solvent-free, general approach to synthesize metastable compounds and fabricate photodetectors from commercially available precursors.