51. Simultaneously Enhancing Photoluminescence Quantum Efficiency and Optical Gain of Polyfluorene via Backbone Intercalation of 2,5‐Dimethyl‐1,4‐Phenylene.
- Author
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Zhang, Qi, Wu, Yinan, Lian, Shaoshan, Gao, Jinxin, Zhang, Sihao, Hai, Gang, Sun, Chen, Li, Xiangchun, Xia, Ruidong, Cabanillas‐Gonzalez, Juan, and Mo, Yueqi
- Subjects
QUANTUM efficiency ,POLYFLUORENES ,DISTRIBUTED feedback lasers ,CONJUGATED polymers ,SOLID-state lasers ,PHOTOLUMINESCENCE - Abstract
Simultaneous enhancement of photoluminescence quantum efficiency (PLQE) and optical gain in semiconducting polymer films is desirable for optically‐ or electrically‐pumped organic solid‐state lasers. In this work, a simple self‐dilution effect is achieved by introducing a small amount (≈10% by weight) of 2,5‐dimethyl‐1,4‐phenylene (DP) units in the backbone of poly(9,9‐dioctylfluorene) (PFO). The resulting copolymers, compared with PFO (PLQE 39%), exhibit a significantly increased PLQE (66%) while keeping similar absorption and photoluminescence profile, concomitant with an enhancement in optical gain properties. The radiative decay rate increases sharply along with a sustaining reduction in the non‐radiative decay rate in these copolymers, following similar principle of physical dilution of a luminescent compound in solution or in a polymer matrix. Among all the copolymers, the one containing 10% DP units exhibits the lowest amplified spontaneous emission/distributed feedback laser threshold (10.9 nJ/1.4 nJ, eightfold reduction), and the highest gain coefficient (54.4 cm−1). The results demonstrate that a moderate DP/fluorene ratio can maximize the beneficial self‐dilution effects. These investigations shed light on new design strategies to achieve conjugated polymers with concurrent high PLQE and large optical gain properties. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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