Conformational control of exciton-polariton physics in metal-poly(9,9-dioctylfluorene)-metal cavities
Conformational control of exciton-polariton physics in metal-poly(9,9-dioctylfluorene)-metal cavities
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DOI：
10.1103/physrevb.98.195306
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发表时间：
2018-09
影响因子：
3.7
通讯作者：
F. L. Roux;D. Bradley
中科院分区：
文献类型：
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作者：
F. L. Roux;D. Bradley
金属-聚(9，9-二辛基荧烯)-金属微腔中的激子-偏振子物理是通过聚合物主链的构象变化来控制的。利用β相链链段分数增加的薄膜样品，系统地研究了同一半导体中含有两个不同激子亚群的腔体的模式特性和由此产生的发光特性。从角度分辨反射率测量中观察到无序玻璃相激子的超强耦合，TE偏振光和TM偏振光的拉比分裂能都超过1.05 eV(超过激子跃迁能量的30%)。然后通过引入β相激子诱导低极化子分支的分裂，并随着激子含量的增加而增加。在所有情况下，光致发光从最低的偏振子分支发出，允许构象控制发射能量及其角度变化。因此，能够实现具有高度饱和的蓝紫光发射的无色散腔。根据推广到两个激子振子情况的完整Hopfield哈密顿量讨论了实验结果。考虑到半导体的分子特征对于准确描述其强耦合行为的重要性，直接考虑了与振动结构的作用的具体关系。
Control is exerted over the exciton-polariton physics in metal-poly(9,9-dioctylfluorene)-metal microcavities via conformational changes to the polymer backbone. Using thin-film samples containing increasing fractions of β -phase chain segments, a systematic study is reported for the mode characteristics and resulting light emission properties of cavities containing two distinct exciton subpopulations within the same semiconductor. Ultrastrong coupling for disordered glassy-phase excitons is observed from angle-resolved reflectivity measurements, with Rabi splitting energies in excess of 1.05 eV (more than 30 % of the exciton transition energy) for both TE- and TM-polarized light. A splitting of the lower polariton branch is then induced via introduction of β -phase excitons and increases with their growing fraction. In all cases, the photoluminescence emanates from the lowermost polariton branch, allowing conformational control to be exerted over the emission energy and its angular variation. Dispersion-free cavities with highly saturated blue-violet emission are thus enabled. Experimental results are discussed in terms of the full Hopfield Hamiltonian generalized to the case of two exciton oscillators. The importance of taking account of the molecular characteristics of the semiconductor for an accurate description of its strong coupling behavior is directly considered, in specific relation to the role of the vibronic structure.