Room Temperature Polariton Lasing in Ladder‐Type Oligo(p‐Phenylene)s with Different π‐Conjugation Lengths

Abstract

Polariton lasing is coherent emission that originates from macroscopic accumulation of polariton population in the ground state and is a promising route toward efficient coherent light sources as population inversion is not necessary. Unlike most Wannier–Mott excitons in inorganic semiconductors, Frenkel excitons created in organic semiconductors have high oscillator strength and high exciton binding energy, which sustain stable exciton–polaritons at room temperature. Herein, room temperature polariton lasing from a novel class of ladder‐type oligo(p‐phenylene)s is demonstrated. The polariton lasers exhibit a nonlinear increase of their spectrally integrated emission, a reduction in spectral linewidth, blueshift of emission peaks, and long‐range spatial coherence when the pump fluence is increased above threshold. By tuning the π‐conjugation length of the molecular structure, the polariton lasing wavelength can be changed from 430 to 457 nm. Optically pumped thresholds of 12 and 17 μJ cm−2 are observed, which are among the lowest values reported for polariton lasing in organic semiconductors.

Polariton condensation in a microcavity using a highly-stable molecular dye

“…Other studies on organic polariton condensation in strongly-coupled microcavities also indicate that the upper polariton branch can be difficult to detect. 4,13,38 Nevertheless, despite the absence of an UPB, we have used a combination of TMR modelling together with a coupled oscillator model (fit shown together with discussion in Fig. S4 of the ESI †) to estimate Rabi splittings between the photon and the different excitonic transitions in this cavity of O 1 = 168 meV, O 2 = 260 meV and O 3 = 227 meV.…”

Exciton‐Polaritons and Their Bose–Einstein Condensates in Organic Semiconductor Microcavities

“…In view of the full‐color emission tunability of BODIPY family, and earlier reports about BODIPY‐Br polariton condensates [ 59 ] with the ability of being nanosecond optical pumped, [ 157 ] it was expected that low‐threshold polariton lasing could be generated over a similar broad range of wavelengths. The other was based on two oligomers, namely oligo( p ‐phenylene)s. [ 57 ] By tuning the π‐conjugation length of the molecular structure, the polariton lasing wavelength could be changed by ≈27 nm. Apart from wavelength tunability, we had lately demonstrated a direction tunable organic polariton laser.…”

“…Meanwhile, in 2D planar cavities, fruitful organic electronically excited-state processes can be dramatically modified due to the formation of cavity polaritons, [6][7][8][9] allowing observation of extraordinary photochemistry and photophysics of organic molecules, such as altered chemical reactions, [10,11,[25][26][27] long-range energy transfer, [28][29][30][31][32][33][34] modulated single/triplet dynamics, [35][36][37][38][39][40][41][42][43][44][45] and enhanced nonlinear optical effects. [46][47][48][49] More importantly, room temperature polariton condensation and related phenomena such as polariton lasing, superfluidity have been demonstrated in planar cavity structures with a broad range of organic materials, [50] including single crystals [51][52][53] and thin films based on conjugated polymers, [54,55] oligomers, [56,57] molecular dyes, [58][59][60] and fluorescent proteins. [61,62] These experimental pr...…”

“…[46][47][48][49] More importantly, room temperature polariton condensation and related phenomena such as polariton lasing, superfluidity have been demonstrated in planar cavity structures with a broad range of organic materials, [50] including single crystals [51][52][53] and thin films based on conjugated polymers, [54,55] oligomers, [56,57] molecular dyes, [58][59][60] and fluorescent proteins. [61,62] These experimental progresses simultaneously resulted in the emergence of promising architectures as tunable coherent light sources, [52,57,60] all optical transistors and switches, [63] polariton superfluid, [64] and future quantum simulations. [65][66][67][68][69][70] However, the development of organic exciton-polaritons and their condensates is still in its infancy as it needs to combine the expertise from, at least, three different subjects: chemistry, quantum optics, and nanophotonics.…”

Realizing Near‐Infrared Laser Dyes through a Shift in Excited‐State Absorption

“…In recent years, organic semiconductor laser diodes (OSLDs) have been intensively researched in terms of materials development, mechanism investigation, and device optimization. [ 1–11 ] OSLDs benefit from advantages such as wavelength tunability, mechanical flexibility, and simple fabrication processes compared with conventional inorganic semiconductor lasers, and therefore show great promise in future optoelectronics. Although the first demonstration of a blue OSLD under current excitation was reported based on a blue laser material known as 4,4′‐bis([ N ‐carbazole]styryl)biphenyl, [ 12 ] the development of OSLDs that cover the full color range is highly demanded to expand the possibilities of their applications.…”