Formation and Encapsulation of All-Inorganic Lead Halide Perovskites at Room Temperature in Metal-Organic Frameworks

Abstract

Improving the stability and tuning the optical properties of semiconducting perovskites are vital for their applications in advanced optoelectronic devices. We present a facile synthetic method for hybrid composites of perovskites and metal-organic frameworks (MOFs). A simple two-step solution-based method without organic surfactants was employed to make all-inorganic lead-halide perovskites (CsPbX 3 ; X = Cl, Br, I, or mixed halide compositions) form directly in the pores of MIL-101 MOF. That is, a polar organic solution of lead halide (PbX 2 ) was impregnated into the MOF pores to give PbX 2 @MIL-101, which was then subjected to a perovskite-formation reaction with cesium halide (CsX) dissolved in methanol. The compositions of the halogen anions in the perovskites can be modulated with various halide precursors, leading to CsPbX 3 @MIL-101 composites with X 3 = Cl 3 , Cl 2 Br, Br 2 Cl, Br 3 , Br 2 I, I 2 Br, and I 3 that exhibit gradual variation of band gap energies and tuned emission wavelengths from 417 to 698 nm.