This indeed led to a gradual expansion of the observation window with pump intensity, which ultimately resulted in slower τR at higher pump intensity due to its non-convergent nature (Figure , Table ). An increase in τD with pump intensity is a well-documented phenomenon for QDs, which was later attributed to optical saturation and brightness heterogeneity. Therefore, the slower τR at higher pump intensity in our case is not surprising, as τD shifted toward longer delay leaving behind a broader observation window with the increasing the excitation power (Figure , Table ). Using conventional FCS, the observation window can be extended by only a few ms by switching the solvent from toluene to octadecene, latter is ~7 times more viscous than toluene. Also, by employing a high excitation power (~100 W/cm 2 ), one can further enhance the observation window by many folds as τD slows down dramatically at high pump intensity due to the optical saturation (Figure and Table ). Interestingly, we observed non-convergence of τR even in octadecene at the highest excitation power (~100 W/cm²), despite it providing the longest observation window size (≤9.7 ms) one can image in the solution phase FCS study (Table ). This unambiguously suggests that the solution phase FCS study is inefficient for studying the blinking dynamics of d-PNCs across all timescales. We are concerned that while further increasing the excitation power would extend the τD and provide a longer observation window, it could also risk damaging the sample. Additionally, there are hardly any solvents available that are benign to PNCs and more viscous than octadecene to replace it and thus enlarge the observation window. All these factors prompted us to switch to sFCS, where, by modulating scanning speed, one can easily access the slower time regime of the blinking dynamics. To confirm that the τR is truly a non-converging parameter, one should record the blinking dynamics in a time window that is extended up to subsecond or to an even longer timescale using sFCS. To our surprise, even the subsecond window of sFCS was found to be insufficient to capture the entire blinking dynamics. Although τR in sFCS study appears at a much longer timescale (11-70 ms) compared to those in octadecene (0.53-1.3 ms) and toluene (0.19-0.77 ms), it still continues to increase further with increasing pump intensity of sFCS at fixed scan speed (Figure , Table ). This observation is analogous to the one observed in power-dependent conventional FCS studies (Figure , Table ). Similar to the τD of conventional FCS, the characteristic timescale of scanning (τS) continues to increase with increasing excitation power, pushing the slower end of the observation window of sFCS toward the longer delay at high pump intensity. This eventually resulted in a longer τR at higher pump intensity in the sFCS study, pointing toward the non-converging nature of τR even in a muchextended subsecond observation window (Figure , Table ). In our sFCS study, we first employed a relatively faster scanning speed of ~4.6 µm/s, which expanded the observation window size to >50 ms (τS) from 9.7 ms (τD) in conventional FCS, the longest diffusion time in octadecene at highest excitation power. With this scanning speed (~4.6 µm/s), and lowest excitation power (~10 W/cm 2 ), we observed τR ~11 ms, which is more than an order of magnitude slower than the ones (~0.19 and ~0.53 ms) observed in toluene and octadecene at similar excitation powers (~5 W/cm 2 ). This trend remains more or less similar across all excitation powers (Tables and). This observation suggests that even a ~50 ms observation window of sFCS fails to converge τR (Figure ). In our subsequent attempt to expand the observation window of sFCS, we increased the excitation power step-wise while maintaining the scan speed fixed at ~4.6 µm/s. This approach resulted in an observation window for blinking studies at high power that is at least twice as long compared to that of the low power. For instance, τS increased from ~96 ms to ~190 ms, accompanied by an increase in τR from ~11 ms to ~70 ms, as the excitation power was raised from ~10 W/cm² to ~750 W/cm² (Figure , Table ). Despite expanding the observation window size to over 100 ms in sFCS, τR still did not converge. This observation is similar to what was observed in conventional FCS with a shorter temporal window. This observation suggests that the τR derived from conventional FCS studies is way faster than the actual. In fact, we are afraid that even sFCS with subsecond observation window may fail to record the entire blinking dynamics. In our next effort, we further extended the temporal size of the observation window while keeping excitation power fixed at ~400 W/cm 2 by reducing the scanning speed step-wise from ~4.6 µm/s to ~2.3 µm/s, and finally to ~1.4 µm/s. This, in turn, resulted in a gradual shift of τS to longer delays, from ~138 ms to ~258 ms, and finally to ~440 ms (Figure 3). To our surprise, τR continued to increase with decreasing scanning speed, without converging, at least up to the window size as big as limited by the 440 ms scanning timescale (Table ). For example, τR increases from ~48 ms to ~86 ms as scanning speed reduces from ~4.6 µm/s to ~1.4 µm/s, respectively. This is a very fascinating observation, and to the best of our knowledge, there is no report in the literature showing non-convergence of the blinking timescale of PNCs using an FCS study.