Figure 1.

PL spectrum of CsPbBr₃ nanocrystals, obtained at 8 K, (a) under nonresonant (405 nm) and (b) under quasi-resonant (520 nm) excitation conditions. A narrowing of the PL band is observed at the lower excitation energy. The laser line situated at the high-energy end of the spectrum in (b) was blocked by the intermediate slit of the spectrometer, such that the data points shown here do not span the entire emission spectrum.