Nanoscale-Resolved Surface-to-Bulk Electron Transport in CsPbBr 3 Perovskite

• Published in: Nano letters 2022-02, Vol.22 (3), p.1067-1074
• Main Authors: Polishchuk, Serhii, Puppin, Michele, Crepaldi, Alberto, Gatti, Gianmarco, Dirin, Dmitry N, Nazarenko, Olga, Colonna, Nicola, Marzari, Nicola, Kovalenko, Maksym V, Grioni, Marco, Chergui, Majed
• Format: Article
• Language: English
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.1c03941

Describing the nanoscale charge carrier transport at surfaces and interfaces is fundamental for designing high-performance optoelectronic devices. To achieve this, we employ time- and angle-resolved photoelectron spectroscopy with ultraviolet pump and extreme ultraviolet probe pulses. The resulting high surface sensitivity reveals an ultrafast carrier population decay associated with surface-to-bulk transport, which was tracked with a sub-nanometer spatial resolution normal to the surface, and on a femtosecond time scale, in the case of the inorganic CsPbBr lead halide perovskite. The decay time exhibits a pronounced carrier density dependence, which is attributed via modeling to enhanced diffusive transport and concurrent recombination. The transport is found to approach an ordinary diffusive regime, limited by electron-hole scattering, at the highest excitation fluences. This approach constitutes an important milestone in our capability to probe hot-carrier transport at solid interfaces with sub-nanometer resolution in a theoretically and experimentally challenging, yet technologically relevant, high-carrier-density regime.