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Phase control for quasi-2D blue emitters by spacer cation engineering


Effect of the alkylammonium tail length in phenyl-alkyl spacer cations in quasi-2D Ruddlesden-Popper perovskites on the phase distribution in low n films (n=2 stoichiometry) is investigated. The increase in the alkyl chain length suppresses the formation of n=1 phase (and consequently higher n phases), which is attributed to the change in the packing arrangement of spacer cations from parallel (one and two carbon atoms alkyl chain) to non-parallel (3 carbon atoms alkyl chain). Single blue emission peak corresponding to n=3 phase (466 nm) and n=2 phase (436 nm) is obtained in the PL spectra of propylphenylammonium quasi-2D perovskites with methylammonium (MA) and formamidinium (FA) cations, respectively. The same trends in phase distribution, namely the reduction in the proportion of n=1 phase with increasing alkyl chain length are observed for both MA- and FA- based perovskites. However, FA-based samples exhibit higher crystallinity but worsened morphology (more pinholes) and less efficient funneling compared to MA-based samples. Consequently, efficient sky-blue LEDs with the highest EQE of 3.35% are obtained for PPA2MAPb2Br7 perovskite.

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Supplementary files

Article information

31 Mar 2020
05 May 2020
First published
07 May 2020

J. Mater. Chem. C, 2020, Accepted Manuscript
Article type

Phase control for quasi-2D blue emitters by spacer cation engineering

H. W. Tam, T. L. Leung, W. Sun, F. Liu, C. Ma, C. S. Kam, I. Lončarić, L. Grisanti, J. Ovčar, Ž. Skoko, J. Popović and A. Djurisic, J. Mater. Chem. C, 2020, Accepted Manuscript , DOI: 10.1039/D0TC01631D

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