Crystal structure and properties of dye-containing organic- inorganic perovskites

The oligothiophene derivative, 5,5‴-bis(aminoethyl) 2,2′:5′,2″:5″, 2‴-quaterthiophene (AEQT), has been incorporated within a lead(II) halide-based perovskite framework. Single crystal X-ray analysis has been used to verify the perovskite framework and examine the ordering of the dye cations within the structure. Thin films of (AEQT)PbX4 (X = Cl, Br, and I) have also been thermally ablated onto quartz substrates and the optical properties of the films have been examined. Strong photoluminescence from the quaterthiophene moiety is observed for X = Cl, with an emission peak at approximately λmax = 532 nm. Similar photoluminescence is observed for the X = Br and I materials, but with progressively less intensity, as the band gap of the inorganic framework gets smaller relative to the LUMO-HOMO gap of the dye molecule. (AEQT)PbCl4 films have also been incorporated as emission layers in light emitting devices (LED) and intense room temperature electroluminescence has been observed.