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

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 (CsPbX3; 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 (PbX2) was impregnated into the MOF pores to give PbX2@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 CsPbX3@ MIL-101 composites with X-3 = Cl-3, Cl2Br, Br2Cl, Bra, Br2I, I2Br, and I-3 that exhibit gradual variation of band gap energies and tuned emission wavelengths from 417 to 698 nm.