Multimodal noncontact atomic force microscopy and Kelvin probe force microscopy investigations of organolead tribromide perovskite single crystals

• Published in: Beilstein journal of nanotechnology Vol. 9; no. 1; pp. 1695 - 1704
• Main Authors: Almadori, Yann, Moerman, David, Martinez, Jaume Llacer, Leclère, Philippe, Grévin, Benjamin
• Format: Journal Article
• Language: English
• Published: Germany Beilstein-Institut zur Föerderung der Chemischen Wissenschaften 2018; Karlsruhe Institute of Technology; Beilstein-Institut
• Subjects: Atomic force microscopy; carrier lifetime; Condensed Matter; Crystal surfaces; Decay rate; Deformation; Electric fields; Experiments; Full Research Paper; Grain boundaries; Illumination; Ion migration; Kelvin probe force microscopy (KPFM); Light; Microscopy; Nanoscience; Nanotechnology; noncontact atomic force microscopy (nc-AFM); organic–inorganic hybrid perovskites; Perovskites; photostriction; Physics; Single crystals; surface photovoltage (SPV); Thin films; Time dependence; time-resolved surface photovoltage; carrier lifetime; single crystals; noncontact atomic force microscopy (nc-AFM); photostriction; ion migration; organic–inorganic hybrid perovskites; surface photovoltage (SPV); Kelvin probe force microscopy (KPFM); time-resolved surface photovoltage
• ISSN: 2190-4286; 2190-4286
• DOI: 10.3762/bjnano.9.161

In this work, methylammonium lead tribromide (MAPbBr 3 ) single crystals are studied by noncontact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM). We demonstrate that the surface photovoltage and crystal photostriction can be simultaneously investigated by implementing a specific protocol based on the acquisition of the tip height and surface potential during illumination sequences. The obtained data confirm the existence of lattice expansion under illumination in MAPbBr 3 and that negative photocarriers accumulate near the crystal surface due to band bending effects. Time-dependent changes of the surface potential occurring under illumination on the scale of a few seconds reveal the existence of slow ion-migration mechanisms. Lastly, photopotential decay at the sub-millisecond time scale related to the photocarrier lifetime is quantified by performing KPFM measurements under frequency-modulated illumination. Our multimodal approach provides a unique way to investigate the interplay between the charges and ionic species, the photocarrier-lattice coupling and the photocarrier dynamics in hybrid perovskites.