Self-Assembled Microdisk Lasers of Perylenediimides

Organic solid-state
lasers (OSSLs) have been a topic of intensive
investigations. Perylenediimide (PDI) derivatives are widely used
in organic thin-film transistors and solar cells. However, OSSLs based
on neat PDIs have not been achieved yet, owing to the formation of
H-aggregates and excimer trap-states. Here, we demonstrated the first
PDI-based OSSL from whispering-gallery mode (WGM) hexagonal microdisk
(hMD) microcavity of N,N′-bis­(1-ethylpropyl)-2,5,8,11-tetrakis­(p-methyl-phenyl)-perylenediimide (mp-PDI)
self-assembled from solution. Single-crystal data reveal that mp-PDI molecules stack into a loosely packed twisted brickstone
arrangement, resulting in J-type aggregates that exhibit a solid-state
photoluminescence (PL) efficiency φ > 15%. Moreover, we found
that exciton-vibration coupling in J-aggregates leads to an exceptional
ultrafast radiative decay, which reduces the exciton diffusion length,
in turn, suppresses bimolecular exciton annihilation (bmEA) process.
These spectral features, plus the optical feedback provided by WGM-hMD
microcavity, enable the observation of multimode lasing as evidenced
by nonlinear output, spectral narrowing, and temporal coherence of
laser emission. With consideration of high carrier-mobility associated
with PDIs, hMDs of mp-PDI are attractive candidates
on the way to achieve electrically driven OSSL.