In Situ Visualization of Assembly and Photonic Signal Processing in a Triplet Light-Harvesting Nanosystem

Real-time
visualization of assembly processes and sophisticated
signal processing at the nanoscale are two challenging topics in photonic
nanomaterials. Here, high-quality light-harvesting crystalline nanorods
were developed by the coassembly of two polypyridyl Ir­(III) and Ru­(II)
metallophosphors, behaving as the antenna chromophore and energy acceptor,
respectively. By using a one-pot or stepwise growth condition, homogeneous
and multiblock heterojunction nanorods were prepared, respectively.
These nanostructures display multicolor phosphorescence from green
to red due to the efficient triplet energy transfer and light-harvesting
capability at low acceptor doping ratios. Heterojunction nanorods
show gradient emission-color switches during different growth stages,
in which the real-time stepwise assembly can be vividly visualized
using fluorescence microscopy techniques. Triplet excitons were successfully
manipulated in both homogeneous and heterojunction nanorods to realize
waveguided green, orange, and red emissions and advanced photonic
signal logics and encoding/decoding on single multiblock heterojunction
nanorod.