Nanocrystals are interesting materials that typically exhibit size-dependent properties, unlike in their bulk macroscopic form. Understanding exactly how the size and even dimensionality affects fundamental optical, energetic and electronic properties is essential for using and optimizing these (nano-)materials. Despite increasingly improving syntheses, nanocrystals are never identical, always experiencing slight differences in structure or composition and thus in their resulting properties. This effect is also referred to as inhomogeneous broadening and can be seen in the difference between photoluminescence spectra of single nanocrystals and large ensembles of them (see image below).
Accordingly, one needs to investigate the nanocrystals individually to understand which properties are intrinsic and which arise due to broadening. One way to achieve this is through a technique known as micro-PL, where PL measurements are conducted on areas typically smaller than one micrometer. For this we have a home-built micro-PL setup, using a tunable white-light laser for excitation. Detection possibilities include a spectrometer and CCD to provide PL spectra or a avalanche photodiode to provide time-resolved PL.
Nonradiative energy transfer between thickness-controlled halide perovskite nanoplatelets
A. Singldinger, M. Gramlich, C. Gruber, C. Lampe, and A. S. Urban
ACS Energy Letters 5 (2020), 1380-1385
Polymer nanoreactors shield perovskite nanocrystals from degradation
V. A. Hintermayr, C. Lampe, M. Löw, J. Roemer, W. Vanderlinden, M. Gramlich, A. X. Böhm, C. Sattler, B. Nickel, T. Lohmueller, and A. S. Urban
Nano Letters 19 (2019), 4928-4933