Gray Victor, Toolan Daniel T W, Dowland Simon, Allardice Jesse R, Weir Michael P, Zhang Zhilong, Xiao James, Klimash Anastasia, Winkel Jurjen F, Holland Emma K, Fregoso Garrett M, Anthony John E, Bronstein Hugo, Friend Richard, Ryan Anthony J, Jones Richard A L, Greenham Neil C, Rao Akshay
Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, U.K.
Department of Chemistry, Ångström Laboratory, Uppsala University, Box 532, SE-751 20 Uppsala, Sweden.
J Am Chem Soc. 2024 Mar 20;146(11):7763-7770. doi: 10.1021/jacs.4c00125. Epub 2024 Mar 8.
Blends comprising organic semiconductors and inorganic quantum dots (QDs) are relevant for many optoelectronic applications and devices. However, the individual components in organic-QD blends have a strong tendency to aggregate and phase-separate during film processing, compromising both their structural and electronic properties. Here, we demonstrate a QD surface engineering approach using electronically active, highly soluble semiconductor ligands that are matched to the organic semiconductor host material to achieve well-dispersed inorganic-organic blend films, as characterized by X-ray and neutron scattering, and electron microscopies. This approach preserves the electronic properties of the organic and QD phases and also creates an optimized interface between them. We exemplify this in two emerging applications, singlet-fission-based photon multiplication (SF-PM) and triplet-triplet annihilation-based photon upconversion (TTA-UC). Steady-state and time-resolved optical spectroscopy shows that triplet excitons can be transferred with near unity efficiently across the organic-inorganic interface, while the organic films maintain efficient SF (190% yield) in the organic phase. By changing the relative energy between organic and inorganic components, yellow upconverted emission is observed upon 790 nm NIR excitation. Overall, we provide a highly versatile approach to overcome longstanding challenges in the blending of organic semiconductors with QDs that have relevance for many optical and optoelectronic applications.
由有机半导体和无机量子点（QD）组成的混合物与许多光电器件应用相关。然而，有机-量子点混合物中的各个组分在成膜过程中具有强烈的聚集和相分离倾向，这会损害它们的结构和电子性能。在此，我们展示了一种量子点表面工程方法，使用与有机半导体主体材料相匹配的具有电子活性、高溶解性的半导体配体，以获得分散良好的无机-有机混合薄膜，这通过X射线和中子散射以及电子显微镜进行了表征。这种方法保留了有机相和量子点相的电子性能，并且还在它们之间创建了一个优化的界面。我们在两个新兴应用中对此进行了举例说明，即基于单线态裂变的光子倍增（SF-PM）和基于三线态-三线态湮灭的光子上转换（TTA-UC）。稳态和时间分辨光谱表明，三线态激子可以以近乎单位效率在有机-无机界面上有效转移，而有机薄膜在有机相中保持高效的单线态裂变（产率为190%）。通过改变有机和无机组分之间的相对能量，在790nm近红外激发下观察到黄色上转换发射。总体而言，我们提供了一种高度通用的方法来克服有机半导体与量子点混合中存在的长期挑战，这与许多光学和光电器件应用相关。
