H‐Shaped Oligofluorenes for Highly Air‐Stable and Low‐Threshold Non‐Doped Deep Blue Lasing

Qian, Yan; Wei, Qi; Pozo, Gonzalo del; Mróz, Marta M.; Lüer, Larry; Casado, Santos; Cabanillas‐González, Juan; Zhang, Qi; Xie, Linghai; Xia, Ruidong; Huang, Wei

doi:10.1002/adma.201305355

Cited by 59 publications

(43 citation statements)

References 25 publications

(40 reference statements)

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“…This is not an indication of low efficiency of the system, but rather a consequence of the low absorption coefficient of the thin film at the pump wavelength (aB90 cm À 1 ; absorbed light, o1%), which does not allow the system to reach its laser threshold. Therefore, in terms of solid-state laser performance, anti-B 18 H 22 cannot, for the time being, rival other existing solidstate, solution-processable, blue-laser media [34][35][36][37][38] . In this regard, further research into the development of new luminescent boranes with stronger absorption properties will ultimately delineate the prospects of efficient and photostable thin-film solid-state borane lasers going forward.…”

Section: Resultsmentioning

confidence: 99%

A borane laser

et al. 2015

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Emission from electronically excited species forms the basis for an important class of light sources-lasers. So far, commercially available solution-processed blue-emitting laser materials are based on organic compounds or semiconductor nanocrystals that have significant limitations: either low solubility, low chemical-and/or photo-stability and/or uncompetitive prices. Here we report a novel and competitive alternative to these existing laser materials that is based on boron hydrides, inorganic cluster compounds with a rich and diverse chemistry. We demonstrate that solutions of the borane anti-B 18 H 22 show, under pulsed excitation, blue laser emission at 406 nm with an efficiency (ratio of output/input energies) of 9.5%, and a photostability superior to many of the commercially available state-of-the-art blue laser dyes. This demonstration opens the doors for the development of a whole new class of laser materials based on a previously untapped resource for laser technology-the boranes.

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Section: Resultsmentioning

confidence: 99%

A borane laser

et al. 2015

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“…The 1PA pumped threshold of the T6 based DFB laser is 600 nJ cm À2 , which is ultra-low in organic semiconductors. The achieved 1PA pumped lasing threshold is better than that of the other types of oligomers (B1 mJ cm À2 ) 50 and starburst macromolecular organic semiconductors (B3 mJ cm À2 ). 9 Also, our 1PA pumped laser threshold is comparable to that (300 nJ cm À2 ) of the pyrene-cored oligomer based lasers.…”

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confidence: 85%

Ultralow-threshold up-converted lasing in oligofluorenes with tailored strong nonlinear absorption

et al. 2015

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ae Nonlinear optical response in organic semiconductors has been an attractive property for many practical applications. For frequency up-converted lasers, to date, conjugated polymers, fluorescent dyes and small organic molecules have been proposed but their performances have been severely limited due to the difficulty in simultaneously achieving strong nonlinear optical response and high performance optical gain. In this work, we show that structurally designed truxene-based star-shaped oligofluorenes exhibit strong structure-property relationships enabling enhanced nonlinear optical response with favorable optical gain performance. As the number of fluorene repeat units in each arm is increased from 3 to 6, these molecules demonstrate a two-photon absorption cross-section as high as 2200 GM, which is comparable to that of linear conjugated polymers. Tailored truxene oligomers with six fluorene units in each arm (T6) show two-photon absorption pumped amplified spontaneous emission with a threshold as low as 2.43 mJ cm À2, which is better than that of the lowest reported threshold in organic semiconductors. Furthermore, we show a frequency up-converted laser using the newly designed and synthesized star-shaped oligomer T6 with a threshold as low as 3.1 mJ cm À2 , which is more than an order of magnitude lower than that of any conjugated polymer. Thus, these oligomers with enhanced nonlinear optical properties are highly attractive for bio-integrated applications such as photodynamic therapy and in vivo bio-sensing.

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“…[4]. The PFO host and F8BT guest polymers were supplied by Xi'an Polymer Light Technology Corporation and were used as received.…”

Section: Methodsmentioning

confidence: 99%

“…[1][2][3][4][5][6] These and other organic gain media can be pumped by compact laser (LD) [7][8][9][10] and lightemit ting (LED) [11,12] diode sources but direct electrical pumping has not been reported yet. Binary blends of conjugated host and guest materials have been used both to enhance LED performance and to reduce optically pumped laser thresholds via efficient exciton generation on the host and/or the guest and rapid hosttoguest Förster resonantenergytransfer (FRET).…”

Section: Introductionmentioning

confidence: 99%

“…[31][32][33][34] We now report a novel host, namely, 3,6bis(2,7di ( [1,1′biphenyl]4yl)9phenyl9Hfluoren 9yl)9octyl9H-carbazole (DBPhFCz), a thermally stable (T g > 240 °C) Hshaped molecule, consisting of bisarylsubstituted fluorene arms bridged at the C9position by a carbazole unit. DBPhFCz possesses stateof theart blue lasing properties [4,34] and, more importantly, has a substantially weaker PA p than PFO, with a growin time that further limits competition, thereby yielding effi cient FRETpumped F8BT SE and lasing. We additionally demonstrate, through a detailed study of different length 9,9dihexylfluorene oligomers and an arylsubstituted terfluorene, that this is a general behavior in short conju gation length hosts, confirming that exciton confinement helps to prevent rapidonset PA p and thus facilitates guest SE.…”

Section: Introductionmentioning

confidence: 99%

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Host Exciton Confinement for Enhanced Förster‐Transfer‐Blend Gain Media Yielding Highly Efficient Yellow‐Green Lasers

Zhang

Liu

Wei

et al. 2018

Adv Funct Materials

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This paper reports state-of-the-art fluorene-based yellow-green conjugated polymer blend gain media using Förster resonant-energy-transfer from novel blue-emitting hosts to yield low threshold (≤7 kW cm −2 ) lasers operating between 540 and 590 nm. For poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) (15 wt%) blended with the newly synthesized 3,6-bis(2,7-di([1,1′-biphenyl]-4-yl)-9-phenyl-9H-fluoren-9-yl)-9-octyl-9H-carbazole (DBPhFCz) a highly desirable more than four times increase (relative to F8BT) in net optical gain to 90 cm −1 and 34 times reduction in amplified spontaneous emission threshold to 3 µJ cm −2 is achieved. Detailed transient absorption studies confirm effective exciton confinement with consequent diffusionlimited polaron-pair generation for DBPhFCz. This delays formation of host photoinduced absorption long enough to enable build-up of the spectrally overlapped, guest optical gain, and resolves a longstanding issue for conjugated polymer photonics. The comprehensive study further establishes that limiting host conjugation length is a key factor therein, with 9,9-dialkylfluorene trimers also suitable hosts for F8BT but not pentamers, heptamers, or polymers. It is additionally demonstrated that the host highest occupied and lowest unoccupied molecular orbitals can be tuned independently from the guest gain properties. This provides the tantalizing prospect of enhanced electron and hole injection and transport without endangering efficient optical gain; a scenario of great interest for electrically pumped amplifiers and lasers.

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H‐Shaped Oligofluorenes for Highly Air‐Stable and Low‐Threshold Non‐Doped Deep Blue Lasing

Cited by 59 publications

References 25 publications

A borane laser

A borane laser

Ultralow-threshold up-converted lasing in oligofluorenes with tailored strong nonlinear absorption

Host Exciton Confinement for Enhanced Förster‐Transfer‐Blend Gain Media Yielding Highly Efficient Yellow‐Green Lasers

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