Abrupt fluorescence intermittency or blinking is long recognized to be characteristic of single nano-emitters. Extended quantum-confined nanostructures also undergo spatially heterogeneous blinking, however, there is no such precedence in dimensionally unconfined (bulk) materials. Here, we report multi-level blinking of entire individual organo-lead bromide perovskite micro-crystals (volume 0.1-3 micron-cuble) under ambient conditions. Extremely high spatiotemporal correlation (>0.9) in intra-crystal emission intensity fluctuations signifies effective communication amongst photogenerated carriers at distal locations (up to ~4 microns) within each crystal. Fused polycrystalline grains also exhibit this intriguing phenomenon, which is rationalized by correlated and efficient migration of carriers to a few transient non-radiative traps, the nature and population of which determine blinking propensity. Observation of spatiotemporally correlated emission intermittency in bulk semiconductor crystals opens up the possibility to design novel devices involving long range (mesoscopic) electronic communication.
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