Shining a new light on molecular biexcitonic processes: novel molecules and DNA origami

在应对气候变化的斗争中，可再生能源是我们最坚定的盟友。太阳能是一种丰富的自然资源，特别是在萨斯喀彻温省，我们每年平均获得2264小时的日照。标准的工业化生产的太阳能电池实现的光-电输出效率只有18%-22%，而且如此多的光不被吸收或吸收，只是以热量的形式消散。依赖于双激子能量转移过程的新材料有可能彻底改变太阳能收集设备中光的捕获和传输效率。这项提议解决了这一变革性的机会。我们将开发一种新的材料，基于天青，最大限度地捕获太阳辐射，因为来自整个太阳光谱的光子可以触发双激子过程。由低能光子产生的激子或激子可以结合在一起产生较高能量的激子，而每个高能激子可以分裂产生两个较低能量的激子。这种单重态裂变(SF)过程可以提高能量转换效率，因为每个吸收的光子都会产生更大的电流。然而，很少有分子满足严格的能级要求，并以适当的强度与邻近分子相互作用，这是发生SF所必需的。我们的新方法是开发一类全新的蔚蓝衍生分子，其中有效的SF发生在异常高的能级上。我们将使用超快光谱学技术可视化和量化参与其双激子过程的无数能量传递路径。我们还将通过将分子绑定到纳米级DNA-折纸结构来控制分子之间的相互作用，从而限制它们的相对位置并精确调整它们的相互作用。通过这种双重方法，我的研究小组将显著扩展我们对已知的具有高效双激子过程的分子的知识，并将基于这些过程开发出坚固、高性能的材料。这项研究将极大地提高光收集设备的效率，并催生新的技术，如新的医学成像模式、基于DNA的药物输送工具和超灵敏的环境探测器。由于这种方法是基于天青烯的，自然的扩展是检测石墨烯中的天青烯类缺陷，这是电子行业寻求的许多基于石墨烯的创新实现的绊脚石。这一结果将有助于将加拿大定位为可再生能源技术领域的一支有影响力的力量，从事这项研究的高素质人员将带着可转移的下一代科技技能进入加拿大劳动力市场。通过支持性和主动性的指导，我的毕业生将弘扬公平、多样性和包容性的价值观。他们的培训将使他们获得知识和工具，继续创新，迈向光明的未来。

In the fight against climate change, renewable energy is our strongest ally. Solar energy is an abundant natural resource, especially in Saskatchewan, where we receive an average of 2,264 hours of sunshine per year. A standard industrially-produced solar cell achieves a light-to-electrical output efficiency of only 18-22%, and so much of the light is not absorbed or absorbed only to be dissipated as heat. New materials that rely on biexcitonic energy-transfer processes have the potential to revolutionize the efficiency with which light is captured and transported in solar-harvesting devices. This proposal addresses this transformative opportunity. We will develop a new class of materials, based on azulenes, that maximize solar-radiation capture, as photons from the entire solar spectrum can trigger biexcitonic processes. Excitations, or excitons, created by low-energy photons can combine to produce higher-energy excitons, while each high-energy exciton can split to produce two lower-energy excitons. This singlet-fission (SF) process can increase power-conversion efficiencies as higher electrical currents result for each photon absorbed. However, few molecules fulfill the strict energy-level requirements, and interact with their neighbouring molecules with the appropriate strength, necessary for SF to occur. Our novel approach is to develop a totally new class of azulene-derived molecules in which efficient SF occurs from unusually-high energy levels. We will visualize and quantify the myriad energy-transfer pathways involved in their biexcitonic processes using ultrafast optical spectroscopy techniques. We will also control interactions between molecules by binding them to nano-scale DNA-origami structures, thus constraining their relative positions and precisely tuning their interactions. Through this dual approach, my research group will markedly extend our knowledge of molecules known to exhibit efficient biexcitonic processes and will develop robust, high-performance materials based upon these processes. This research will drastically improve the efficiency of light-harvesting devices and spawn new technologies, such as new medical-imaging modalities, DNA-based drug delivery vehicles, and ultrasensitive environmental detectors. As this approach is based on azulenes, a natural extension is to detect azulene-like defects in graphene, which are a stumbling block in bringing to fruition many graphene-based innovations sought by the electronics industry. The results will help to position Canada as an influential force in renewable energy technologies, and the highly-qualified personnel working on this research will enter the Canadian labour market with transferable next-generation skills in science and technology. Through supportive and proactive mentorship, my graduates will carry forward values of equity, diversity, and inclusivity. Their training will empower them with the knowledge and tools to continue innovating towards a bright future.