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 diffusion‐limited 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.

中文翻译：

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主机激子限制，以增强Förster-Transfer-Blend增益介质产生高效的黄绿色激光器

本文报道了使用新型新型发色主体的Förster共振能量转移技术产生的最先进的芴基黄绿色共轭聚合物共混增益介质，可产生在540至540之间工作的低阈值（≤7 kW cm ^-2）激光器和590 nm。对于聚（9,9-二辛基芴-共-苯并噻二唑）（F8BT）（15 wt％）与新合成的3,6-二（2,7-di（[1,1'-联苯] -4-基）‐9‐苯基‐9H‐芴‐9‐基）‐9‐辛基‐9H–咔唑（DBPhFCz）的90％^-1和34倍的净光学增益（相对于F8BT）要高出四倍以上将放大的自发发射阈值降低到3 µJ cm ^-2已完成。详细的瞬态吸收研究证实了有效的激子约束，并因此产生了DBPhFCz的扩散限制的极化子对。这将延迟主机光诱导吸收的形成足够长的时间，以使得能够建立光谱重叠的来宾光学增益，并解决了共轭聚合物光子学的长期存在的问题。全面的研究进一步证明，限制宿主的共轭长度是其中的关键因素，9,9-二烷基芴三聚体也适合用于F8BT，但不适用于五聚体，七聚体或聚合物。另外证明，可以独立于客体增益特性来调节宿主的最高占据和最低未占据的分子轨道。这为增强电子和空穴的注入和传输提供了诱人的前景，而又不会危及有效的光学增益。电泵放大器和激光器引起了人们极大的兴趣。