15 CLIM can also extract information on the photophysical properties of the sample. By analyzing the intensity traces of each CLIM cluster, -here corresponding to the structural grains -we gain insights into the nature of the nonradiative recombination (NR) centers and their impact on the film's properties. If there was only one NR center per grain, switching between active and inactive states with a 20 defined rate, the PL trace would exhibit a "telegraph signal" with distinct on (high PL) and off (low PL) levels,(64-66) However, as the number of NR centers increases and their properties vary, it becomes challenging to identify clear intensity levels in the fluctuations which is frequently observed for perovskite crystals (Figure ). Recently, some of us demonstrated that the power spectral density (PSD) of PL traces enables 25 unbiased analysis of the PL fluctuation kinetics (see Supporting Note VII). The shape of the PSDs can vary from a Lorentzian function (indicative of a single type of trap) to a power law, depending on the fluctuations' behavior. The origin of the latter is still debated,(69) but it can be explained by the presence of multiple NR centers with switching rates spanning several orders of magnitude. , PSDs of all the samples tend to saturate at lower frequencies ( 1 Hz), indicating the presence of a characteristic timescale for these fluctuations (Figure ). The high frequency range resembles a power law with slope close to 2 with a Lorentzian PSD. This generic behavior holds for most of the analyzed traces across all three 35 samples: MAPI-LG, MAPI-SG and MAPI-POR, and can be described by stretched Lorentzian function, see Eq.(S7.1) in Supporting Note VII.