Generating Long-Lived Triplet Excited States in Narrow Bandgap Conjugated Polymers.
Generating Long-Lived Triplet Excited States in Narrow Bandgap Conjugated Polymers.
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DOI：
10.1021/jacs.2c12008
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发表时间：
2023-02-15
影响因子：
15
通讯作者：
Dimitrov, Stoichko D.
中科院分区：
文献类型：
--
作者：
Marin-Beloqui, Jose M.;Congrave, Daniel G.;Toolan, Daniel T. W.;Montanaro, Stephanie;Guo, Junjun;Wright, Iain A.;Clarke, Tracey M.;Bronstein, Hugo;Dimitrov, Stoichko D.
窄带隙共轭聚合物是一类被广泛研究的有机半导体，但它们的激发态通常具有非常短的寿命，限制了它们的应用范围。克服短寿命的一种方法是填充长寿命的三重态，这种三重态禁止弛豫到基态。然而，窄带隙聚合物薄膜的三重态寿命通常被限制在几微秒内。本文研究了以经典苯二噻吩单体单元为基础，具有增溶烷基侧链C16和C2C6的红致共轭聚合物的膜形态对三重态动力学的影响，并利用Pd卟啉增敏作为进一步改变三重态动力学的策略。利用瞬态吸收光谱，我们证明了更结晶的非敏化聚合物C2C6的三重态寿命为0.45 ms，比通常报道的长2-3个数量级，而无定形的C16只有5 μs的寿命。增加的部分原因是由于在更结晶的C2C6中延迟了双分子电子-空穴复合，在C2C6中电荷复合的能量势垒更高。通过将5%的Pd卟啉共价加入到C16聚合物中，还获得了0.4 ms的三重态寿命，这在聚合物和卟啉之间引入了额外的能量转移步骤，延迟了三重态动力学，并将聚合物三重态产率提高了7.9倍。这项工作展示了在窄带隙共轭聚合物中产生寿命最长的三重态激发态的两种合成方法，这在从有机电子到传感器和生物应用的广泛领域是必要的。
Narrow bandgap conjugated polymers are a heavily studied class of organic semiconductors, but their excited states usually have a very short lifetime, limiting their scope for applications. One approach to overcome the short lifetime is to populate long-lived triplet states for which relaxation to the ground state is forbidden. However, the triplet lifetime of narrow bandgap polymer films is typically limited to a few microseconds. Here, we investigated the effect of film morphology on triplet dynamics in red-emitting conjugated polymers based on the classic benzodithiophene monomer unit with the solubilizing alkyl side chains C16 and C2C6 and then used Pd porphyrin sensitization as a further strategy to change the triplet dynamics. Using transient absorption spectroscopy, we demonstrated a 0.45 ms triplet lifetime for the more crystalline nonsensitized polymer C2C6, 2–3 orders of magnitude longer than typically reported, while the amorphous C16 had only a 5 μs lifetime. The increase is partly due to delaying bimolecular electron–hole recombination in the more crystalline C2C6, where a higher energy barrier for charge recombination is expected. A triplet lifetime of 0.4 ms was also achieved by covalently incorporating 5% of Pd porphyrin into the C16 polymer, which introduced extra energy transfer steps between the polymer and porphyrin that delayed triplet dynamics and increased the polymer triplet yield by 7.9 times. This work demonstrates two synthetic approaches to generate the longest-lived triplet excited states in narrow bandgap conjugated polymers, which is of necessity in a wide range of fields that range from organic electronics to sensors and bioapplications.
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影响因子：
41.2
作者：
Kosco J;Bidwell M;Cha H;Martin T;Howells CT;Sachs M;Anjum DH;Gonzalez Lopez S;Zou L;Wadsworth A;Zhang W;Zhang L;Tellam J;Sougrat R;Laquai F;DeLongchamp DM;Durrant JR;McCulloch I
通讯作者：
McCulloch I
影响因子：
5.5
作者：
Hou, Jianhui;Park, Mi-Hyae;Yang, Yang
通讯作者：
Yang, Yang
影响因子：
4
作者：
Chen, FC;He, GF;Yang, Y
通讯作者：
Yang, Y
影响因子：
41.2
作者：
Chen, Chengjian;Chi, Zhenguo;Liu, Bin
通讯作者：
Liu, Bin
影响因子：
4.3
作者：
Kuila, Suman;Ghorai, Anaranya;George, Subi J.
通讯作者：
George, Subi J.