# Tunable Broad Light Emission from 3D Hollow'' Bromide Perovskites through Defect Engineering

### Citation:

Spanopoulos, I. ; Hadar, I. ; Ke, W. ; Guo, P. ; Mozur, E. M. ; Morgan, E. ; Wang, S. ; Zheng, D. ; Padgaonkar, S. ; Reddy, G. N. M. ; et al. Tunable Broad Light Emission from 3D Hollow'' Bromide Perovskites through Defect Engineering. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 2021, 143, 7069-7080.

MAY 12

### Abstract:

Hybrid halide perovskites consisting of corner-sharing metal halide octahedra and small cuboctahedral cages filled with counter cations have proven to be prominent candidates for many high-performance optoelectronic devices. The stability limits of their three-dimensional perovskite framework are defined by the size range of the cations present in the cages of the structure. In some cases, the stability of the perovskite-type structure can be extended even when the counterions violate the size and shape requirements, as is the case in the so-called “hollow” perovskites. In this work, we engineered a new family of 3D highly defective yet crystalline “hollow” bromide perovskites with general formula (FA)1–x(en)x(Pb)1–0.7x(Br)3–0.4x (FA = formamidinium (FA+), en = ethylenediammonium (en2+), x = 0–0.44). Pair distribution function analysis shed light on the local structural coherence, revealing a wide distribution of Pb–Pb distances in the crystal structure as a consequence of the Pb/Br-deficient nature and en inclusion in the lattice. By manipulating the number of Pb/Br vacancies, we finely tune the optical properties of the pristine FAPbBr3 by blue shifting the band gap from 2.20 to 2.60 eV for the x = 0.42 en sample. A most unexpected outcome was that at > 0.33 en incorporation, the material exhibits strong broad light emission (1% photoluminescence quantum yield (PLQY)) that is maintained after exposure to air for more than a year. This is the first example of strong broad light emission from a 3D hybrid halide perovskite, demonstrating that meticulous defect engineering is an excellent tool for customizing the optical properties of these semiconductors.

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Last updated on 12/01/2021