Study of CsPbBr$_{3}$ nanocrystals and their agglomerates by combined scanning probe microscopy and optical spectrometry

The electric, piezoelectric, and optical properties of colloidally synthesized CsPbBr$_{3}$ nanocrystals (NCs) are studied by combined scanning probe microscopy and optical spectrometry. It is found that the CsPbBr$_{3}$ NCs have a cubic shape with an edge length of 10 nm. When deposited on a substrate, these NCs gather into faceted agglomerates up to several hundred nanometers in size. It is shown that the photoluminescence spectra contain, in addition to the main narrow edge-luminescence line (2.47 eV), two additional broad defect lines lying 40 and 200 meV lower than the main line. The NC agglomerates have a low surface potential ($\sim$ 20–30 mV) and contain a small amount of charges. It is shown that piezoelectric modulus $d_{33}$ of CsPbBr$_{3}$ NC agglomerates does not exceed 1 pm/V.