Plasmon-induced Triplet Energy Transfer (PITET) for Photon Upconversion

化学部的大分子、超分子和纳米化学项目将通过该奖项支持加州大学河滨分校（UCR）的李明唐博士研究等离子体系统的能量传递过程。等离子体动力学是指金属中束缚松散的电子在光诱导下的振荡。该研究对催化、成像和能量转换应用具有重要意义。尺寸在纳米量级的微小金属颗粒因其在彩色玻璃窗上的美丽而受到历史的珍视。彩色玻璃的鲜艳色彩是由金属纳米粒子支持的等离子体对光的强烈吸收和散射引起的。唐博士的团队正在进行基础研究，以寻求有效地将储存在金属纳米颗粒中的等离子体激元能量转移到邻近的化学分子中。这项研究的目的是提供一种机制，以防止系统通过光的快速散射或能量作为热量的耗散而产生不必要的能量损失。这些进展对金属纳米粒子的发展至关重要，因为它们有望应用于光催化和太阳能电池。该团队设计并合成了各种纳米材料结构。等离激元被严格限制在奈米级的金属架构内，然后被表征为调整系统，在光激活时执行有用的工作。这项研究还对南加州的内陆帝国项目的公众参与产生了更广泛的影响。这项拓展计划包括在当地小学和学前班进行互动演示和科学活动，由本科生和研究生领导。UCR的Ming Lee Tang团队正在研究等离子体诱导的三重态能量转移。目标是利用金属纳米天线捕获的光进行光子上转换，这是一个将来自非相干源（如太阳）的低能量光子转换为有用的高能光子的过程。本研究中基于贵金属的新型吸光纳米结构可以吸收近红外光子，从而从邻近的蒽基和苝基发色团中产生紫色光子发射。具体来说，银纳米棱镜和金纳米棒的局部表面等离子体共振调谐在1.5和1.8 eV之间，预计将与发色团的最低激发三重态共振，从而使分子三重态光敏化。稳态光子上转换测量将用于量化等离子体诱导三重态能量转移的效率。时间分辨光致发光和瞬态吸收测量提供了产率和三重态能量转移速率的独立测量。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With this award, the Macromolecular, Supramolecular, and Nanochemistry Program in the Chemistry Division is supporting Dr. Ming Lee Tang at the University of California Riverside (UCR) to study the energy transfer process of plasmonic systems. Plasmonics refers to light-induced oscillation of loosely bound electrons in metals. This research is important for catalysis, imaging, and energy conversion applications. Minuscule metal particles with dimensions on the order of nanometers have been treasured historically for their beauty in stained glass windows. The vivid colors in stained glass arise from the strong absorption and scattering of light due to plasmons supported by the metal nanoparticles. Dr. Tang’s team is conducting fundamental research that addresses that seeks to efficiently transfer the energy stored as plasmons in metal nanoparticles to neighboring chemical molecules. The research aims to provide mechanisms to prevent the system from unwanted energy loss through rapid scattering of light or dissipation of energy as heat. Such advances are essential for the development of metal nanoparticles for intended applications in photocatalysis and in solar cells. The team designs and synthesizes various nanomaterial architectures. Plasmons tightly confined within the nanoscale metal architectures are then characterized to tune the system to perform useful work upon light activation. This research also has broader impacts of engaging the general public in the Inland Empire program in Southern California. This outreach program includes interactive demonstrations and science activities at local elementary schools and pre-schools that are led by undergraduate and graduate students.Dr. Ming Lee Tang’s team at UCR is investigating plasmon-induced triplet energy transfer. The goal is to use light captured by metal nano-antennas for photon upconversion, a process of converting low energy photons from incoherent sources such as the sun to useful high energy photons. Novel light-absorbing nanostructures based on noble metals in this research can absorb near-infrared photons to produce violet photon emissions from neighboring anthracene- and perylene-based chromophores. Specifically, silver nanoprisms and gold nanorods with their localized surface plasmon resonance tuned between 1.5 and 1.8 eV are expected to be resonant with the lowest excited triplet states of the chromophores, so as to photosensitize the molecular triplet states across an oxide barrier. Steady-state photon upconversion measurements will be used to quantify the efficiency of plasmon-induced triplet energy transfer. Time resolved photoluminescence and transient absorption measurements provide independent measurements of the yield and rate of the triplet energy transfer.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.