Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States.
J Am Chem Soc. 2022 Mar 2;144(8):3527-3534. doi: 10.1021/jacs.1c12207. Epub 2022 Feb 21.
Leveraging triplet excitons in semiconductor quantum dots (QDs) in concert with surface-anchored molecules to produce long-lifetime thermally activated delayed photoluminescence (TADPL) continues to emerge as a promising technology in diverse areas including photochemical catalysis and light generation. All QDs presently used to generate TADPL in QD/molecule constructs contain toxic metals including Cd(II) and Pb(II), ultimately limiting potential real-world applications. Here, we report newly conceived blue-emitting TADPL-producing nanomaterials featuring InP QDs interfaced with 1- and 2-naphthoic acid (1-NA and 2-NA) ligands. These constitutional isomers feature similar triplet energies but disparate triplet lifetimes, translating into InP-based TADPL processes displaying two distinct average lifetime ranges upon cooling from 293 to 193 K. The time constants fall between 4.4 and 59.2 μs in the 2-NA-decorated InP QDs while further expanding between 84.2 and 733.2 μs in the corresponding 1-NA-ligated InP materials, representing a 167-fold time window. The resulting long-lived excited states enabled facile bimolecular triplet sensitization of O phosphorescence in the near-IR and promoted sensitized triplet-triplet annihilation photochemistry in 2,5-diphenyloxazole. We speculate that the discovery of new nanomaterials exhibiting TADPL lies on the horizon as myriad QDs can be readily derivatized using isomers of numerous classes of surface-anchoring chromophores yielding precisely regulated photophysical properties.
利用半导体量子点 (QD) 中的三重激子与表面锚定分子协同作用产生长寿命热激活延迟光致发光 (TADPL)，这一技术在包括光化学催化和发光在内的多个领域继续展现出巨大的潜力。目前用于在 QD/分子结构中产生 TADPL 的所有 QD 都包含有毒金属，如 Cd(II) 和 Pb(II)，这最终限制了其在现实世界中的潜在应用。在这里，我们报告了一种新构想的蓝色发射 TADPL 产生纳米材料，其特征在于具有 1-和 2-萘酸（1-NA 和 2-NA）配体的 InP QD。这些结构异构体具有相似的三重态能量，但三重态寿命不同，这导致基于 InP 的 TADPL 过程在从 293 K 冷却到 193 K 时显示出两个不同的平均寿命范围。在 2-NA 修饰的 InP QD 中，时间常数在 4.4 和 59.2 μs 之间，而在相应的 1-NA 配位 InP 材料中进一步扩展到 84.2 和 733.2 μs，代表了 167 倍的时间窗口。由此产生的长寿命激发态使近红外处的 O 磷光的双分子三重态敏化变得容易，并促进了 2,5-二苯并恶唑中的敏化三重态-三重态湮灭光化学反应。我们推测，由于可以使用众多类表面锚定发色团的异构体容易地衍生出大量的 QD，因此具有 TADPL 特性的新型纳米材料的发现即将到来，从而可以精确调节其光物理性质。
