Waterproof perovskites: High fluorescence quantum yield and stability from a methylammonium lead bromide/formate mixture in water

Yeasin Khan, Yohan Ahn, Hyuna Lee, Jaeki Jeong, Yun Seop Shin, Je Seung Lee, Jang Hyuk Kwon, Jin Young Kim, Hoon Sik Kim, Jung Hwa Seo, Bright Walker

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

We’ve observed intense fluorescence from the surface of lead formate crystals when they are precipitated from a CH3NH3PbBr3(MAPbBr3) perovskite precursor solution. The crystals exhibit emission in the range of 500-550 nm with a photoluminescence quantum yield (PLQY) of up to 70%. The fluorescence is stable in water and at elevated temperature without significant decrease in PLQY for months, conditions which instantly decompose MAPbBr3. Fluorescence occurred with the highest quantum efficiency of 70% at an optimal 1?:?0.3 molar ratio of methylammonium formate and lead bromide and decreased rapidly for other ratios. Fluorescence was quenched using other halides (Cl or I) or other cations (Cs, ethylammonium, propylammonium,etc.). Single crystal analysis indicates that the material possesses the lead formate structure with lattice parameters which are identical to pristine lead formate, however, analysis of the particles by EDX, XPS and fluorescence microscopy confirms the presence of Br and fluorescence emission on the particle surfaces. The observed material characteristics indicate that the emissive species consists of a mixed-valence surface layer of Pb coordinated to both Br and formate ligands.

Original languageEnglish
Pages (from-to)5873-5881
Number of pages9
JournalJournal of Materials Chemistry C
Volume8
Issue number17
DOIs
StatePublished - 7 May 2020

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