We study one‐dimensional metal halide perovskite crystals encapsulated in single‐wall nanotubes, so‐called picoperovskites, using optical spectroscopy. Polarized micro‐photoluminescence (PL) reveals bright emission from aligned bundles of picoperovskites with clear linear polarization along the bundle axis. This emission is redshifted with respect to bulk perovskite samples using the same constituents. Temperature‐dependent, time‐resolved micro‐PL shows extraordinarily long PL lifetimes of the picoperovskites at low temperatures, reaching several hundred nanoseconds and exceeding those of bulk perovskites by two orders of magnitude.
Tomoscheit et al. (Sun,) studied this question.