Gray Victor, Drake William, Allardice Jesse R, Zhang Zhilong, Xiao James, Congrave Daniel G, Royakkers Jeroen, Zeng Weixuan, Dowland Simon, Greenham Neil C, Bronstein Hugo, Anthony John E, Rao Akshay
Cavendish Laboratory, University of Cambridge J. J. Thomson Avenue Cambridge CB3 0HE UK
Department of Chemistry - Ångström Laboratory, Uppsala University Box 523 751 20 Uppsala Sweden.
J Mater Chem C Mater. 2022 Oct 11;10(43):16321-16329. doi: 10.1039/d2tc03470k. eCollection 2022 Nov 10.
Quantum dot-organic semiconductor hybrid materials are gaining increasing attention as spin mixers for applications ranging from solar harvesting to spin memories. Triplet energy transfer between the inorganic quantum dot (QD) and organic semiconductor is a key step to understand in order to develop these applications. Here we report on the triplet energy transfer from PbS QDs to four energetically and structurally similar tetracene ligands. Even with similar ligands we find that the triplet energy transfer dynamics can vary significantly. For TIPS-tetracene derivatives with carboxylic acid, acetic acid and methanethiol anchoring groups on the short pro- side we find that triplet transfer occurs through a stepwise process, mediated a surface state, whereas for monosubstituted TIPS-tetracene derivative 5-(4-benzoic acid)-12-triisopropylsilylethynyl tetracene (BAT) triplet transfer occurs directly, albeit slower, a Dexter exchange mechanism. Even though triplet transfer is slower with BAT the overall yield is greater, as determined from upconverted emission using rubrene emitters. This work highlights that the surface-mediated transfer mechanism is plagued with parasitic loss pathways and that materials with direct Dexter-like triplet transfer are preferred for high-efficiency applications.
量子点-有机半导体混合材料作为自旋混合器在从太阳能收集到自旋存储器等各种应用中受到越来越多的关注。无机量子点（QD）与有机半导体之间的三线态能量转移是开发这些应用时需要理解的关键步骤。在此，我们报告了从硫化铅量子点到四种能量和结构相似的并四苯配体的三线态能量转移。即使使用相似的配体，我们发现三线态能量转移动力学仍可能有显著差异。对于在短边带有羧酸、乙酸和甲硫醇锚定基团的三异丙基硅乙炔基并四苯（TIPS-并四苯）衍生物，我们发现三线态转移通过一个由表面态介导的逐步过程发生，而对于单取代的TIPS-并四苯衍生物5-（4-苯甲酸）-12-三异丙基硅乙炔基并四苯（BAT），三线态转移直接发生，尽管速度较慢，通过德克斯特交换机制。尽管BAT的三线态转移较慢，但使用红荧烯发射体通过上转换发射确定其总产率更高。这项工作突出表明，表面介导的转移机制存在寄生损耗途径，对于高效应用而言，具有类似直接德克斯特三线态转移的材料更受青睐。
