2 research outputs found
Zero-Dimensional Cs<sub>4</sub>PbBr<sub>6</sub> Perovskite Nanocrystals
Perovskite
nanocrystals (NCs) have become leading candidates for
solution-processed optoelectronics applications. While substantial
work has been published on 3-D perovskite phases, the NC form of the
zero-dimensional (0-D) phase of this promising class of materials
remains elusive. Here we report the synthesis of a new class of colloidal
semiconductor NCs based on Cs<sub>4</sub>PbBr<sub>6</sub>, the 0-D
perovskite, enabled through the design of a novel low-temperature
reverse microemulsion method with 85% reaction yield. These 0-D perovskite
NCs exhibit high photoluminescence quantum yield (PLQY) in the colloidal
form (PLQY: 65%), and, more importantly, in the form of thin film
(PLQY: 54%). Notably, the latter is among the highest values reported
so far for perovskite NCs in the solid form. Our work brings the 0-D
phase of perovskite into the realm of colloidal NCs with appealingly
high PLQY in the film form, which paves the way for their practical
application in real devices
Inside Perovskites: Quantum Luminescence from Bulk Cs<sub>4</sub>PbBr<sub>6</sub> Single Crystals
Zero-dimensional
perovskite-related structures (0D-PRS) are a new
frontier of perovskite-based materials. 0D-PRS, commonly synthesized
in powder form, manifest distinctive optical properties such as strong
photoluminescence (PL), narrow emission line width, and high exciton
binding energy. These properties make 0D-PRS compelling for several
types of optoelectronic applications, including phosphor screens and
electroluminescent devices. However, it would not be possible to rationally
design the chemistry and structure of these materials, without revealing
the origins of their optical behavior, which is contradictory to the
well-studied APbX<sub>3</sub> perovskites. In this work, we synthesize
single crystals of Cs<sub>4</sub>PbBr<sub>6</sub> 0D-PRS, and investigated
the origins of their unique optical and electronic properties. The
crystals exhibit a PL quantum yield higher than 40%, the highest reported
for perovskite-based single crystals. Time-resolved and temperature
dependent PL studies, supported by DFT calculations, and structural
analysis, elucidate an emissive behavior reminiscent of a quantum
confined structure rather than a typical bulk perovskite material