Madigan Conor F, Bulović Vladimir
Lab of Organic Optics and Electronics, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Phys Rev Lett. 2003 Dec 12;91(24):247403. doi: 10.1103/PhysRevLett.91.247403. Epub 2003 Dec 9.
The photoluminescence (PL) of the red laser dye DCM2, doped into blended thin films of polystyrene (PS) and the polar small molecule camphoric anhydride (CA), redshifts as the CA concentration increases. The DCM2 PL peaks at 2.20 eV (lambda=563 nm) for pure PS films and shifts to 2.05 eV (lambda=605 nm) for films with 24.5% CA (by mass). The capacitively measured electronic permittivity also increases from epsilon=2.4 to epsilon=5.6 with CA concentration. These results are consistent with the theory of solvatochromism developed for organic molecules in liquid solvents. To our knowledge, this work is the first application of a quantitative theory of solvation to organic molecules in amorphous thin films with continuously controllable permittivity, and demonstrates that "solid state solvation" can be used to predictably tune exciton energies in organic thin film structures.
掺杂在聚苯乙烯（PS）和极性小分子樟脑酸酐（CA）混合薄膜中的红色激光染料DCM2的光致发光（PL）随着CA浓度的增加而发生红移。对于纯PS薄膜，DCM2的PL峰值在2.20电子伏特（λ=563纳米），而对于含有24.5% CA（质量分数）的薄膜，PL峰值则移至2.05电子伏特（λ=605纳米）。通过电容测量得到的电子介电常数也随着CA浓度的增加从ε=2.4增大到ε=5.6。这些结果与为液体溶剂中的有机分子所发展的溶剂化显色理论相一致。据我们所知，这项工作首次将溶剂化定量理论应用于具有连续可控介电常数的非晶态薄膜中的有机分子，并证明“固态溶剂化”可用于可预测地调节有机薄膜结构中的激子能量。
