Intrinsic broadband white light emission has been observed in layered hybrid organic-inorganic perovskites with the formula (R-NH3+)PbBr4 and previously correlated to static lattice distortions. The structure and relevant electronic states of the inorganic layer are impacted by the choice of the organic spacer cation (R-NH3+). The emission and structural dependence on the organic cation suggest the movement of the organic moieties within the crystal may play a role in the inorganic octahedral tilt angles and, therefore, broadband emission. We have prepared a series of lead bromide HOIPs with varying white light emission; (nBA)2PbBr4, (ODA)PbBr4, (GABA)2PbBr4 (nBA = n-butylammonium, ODA = 1,8-diaminooctammonium, GABA = 4-aminobutyric acid). Using quasielastic neutron scattering and photoluminescence, we correlate more intense broadband emission with materials exhibiting slower cation dynamics. Slower cation dynamics compared to (nBA)2PbBr4 were observed concurrently with an increase in broadband emission for the ODA and GABA-derived samples. This work shows the intensity of the observed emission is dependent on the lattice dynamics and the organic cation, suggesting these dynamics are coupled.

Correlating broadband emission and structural dynamics in layered hybrid perovskites

ACS Fall 2021

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