White CsPbBr3: Characterizing the One-Dimensional Cesium Lead Bromide Polymorph

Inorganic lead halide perovskites have gained immense scientific interest for optoelectronic applications. In this work, we present a one-dimensional polymorph of cesium lead bromide (delta-CsPbBr3) synthesized through a simple anion-exchange reaction, wherein distorted edge-sharing PbBr(6)octahedra form 1D chains isolated by Cs ions.delta-CsPbBr(3)was characterized byRamanspectroscopy, X-ray diffraction,Pb-207 and(133)Cs solid-state NMR, and by optical emission and absorption spectroscopies. This non-perovskite material irreversibly transforms into the well-known three-dimensional perovskite phase (gamma-CsPbBr3) upon heating to above 151 degrees C. The indirect bandgap was determined by absorption measurements and calculation to be 2.9 eV.delta-CsPbBr(3)exhibits broadband yellow photoluminescence with a quantum yield of 3.2 %+/- 0.2 % at room temperature and 95 %+/- 5 % at 77 K, and this emission is attributed to the recombination of self-trapped excitons. This study emphasizes that the metastable delta-CsPbBr(3)may be a persistent, concomitant phase in Cs-Pb-Br-containing materials systems, such as those used in solar cells and LEDs, and it showcases the characterization tools used for its detection.