Morphology-Independent Stable White-Light Emission from Self-Assembled Two-Dimensional Perovskites Driven by Strong Exciton–Phonon Coupling to the Organic Framework

Hybrid
two-dimensional (2D) lead halide perovskites have been employed
in optoelectronic applications, including white-light emission for
light-emitting diodes (LEDs). However, until now, there have been
limited reports about white-light-emitting lead halide perovskites
with experimental insights into the mechanism of the broadband emission.
Here, we present white-light emission from a 2D hybrid lead chloride
perovskite, using the widely known phenethylammonium cation. The single-crystal
X-ray structural data, time-resolved photophysical measurements, and
density functional theory calculations are consistent with broadband
emission arising from strong exciton–phonon coupling with the
organic lattice, which is independent of surface defects. The phenethylammonium
lead chloride material exhibits a remarkably high color rendering
index of 84, a CIE coordinate of (0.37,0.42), a CCT of 4426, and photostability,
making it ideal for natural white LED applications.