Tailoring organic molecular structure to achieve singlet fission for photovoltaic applications

太阳能是可再生能源部门的一种关键资源，但由于效率从根本上受到限制，它没有发挥其潜力。单重态裂变通过将一个较高能量的光子转变为两个较低能量的光子，极大地提高了光伏发电的光收集效率，超过了Shockley-Queisser限制。尽管经过了近十年的研究，但这项技术的进步一直受到限制，因为只有有限的合适分子可以满足发生单线态裂变的严格能量要求，更少的分子表现出最佳的分子堆积和光稳定性，使这一过程能够在现实世界中应用。Cibalackrots(工业靛蓝染料的衍生物)，由于其优异的光稳定性、高的消光系数和理想的预测三重态能量，是非常有吸引力的单态裂变候选者。虽然在能量上是可行的，但以前的工作表明，它们的非理想分子构象阻止了促进单线态裂变所需的有效的分子间轨道重叠。该项目旨在与化学家合作，阐明对Cibalackrots化学结构的简单、明智的改变是否可以在不牺牲分子稳定性的情况下产生难以捉摸的单线态裂变潜力。表征潜在的单线态裂变动力学对于展示改进的分子结构如何积极影响这些分子的光物理至关重要。这将通过使用广泛的尖端技术来实现，例如超快飞秒瞬时吸收光谱、电子顺磁共振以及X射线衍射测量。这一交叉考试的目的是通过分析分子堆积结构来补充对光物理学的理解。这将使我们更广泛地理解分子设计的后果，并检验我们可以量身定做分子结构以利用单态裂变应用于可再生能源和更清洁的环境未来的假设。

Solar energy is a key resource in the renewable energy sector, yet it does not fulfil its potential due to fundamentally restricted efficiency. Singlet fission has the potential to significantly enhance the efficiency of photovoltaic light harvesting beyond this Shockley-Queisser limit by transforming one higher energy photon into two lower energy photons. Despite almost a decade of research, the progress of this technology has been hindered by the limited selection of suitable molecules that can satisfy the strict energetic requirements for singlet fission to occur, with even fewer exhibiting optimal molecular packing and photostability for the process to be viable for real-world application. Cibalackrots (derivatives of industrial indigo dyes), are highly attractive candidates for singlet fission due to their superior photostability, high extinction coefficient and ideal predicted triplet energy. While energetically viable, previous works suggest their non-ideal molecular conformation prevents efficient intermolecular orbital overlap required to facilitate singlet fission. This project aims to collaborate with chemists to elucidate if simple, judicious alterations in chemical structure of Cibalackrots can give rise to the elusive singlet fission potential desired without sacrificing molecular stability.Characterising the underlying singlet fission dynamics is crucial in demonstrating how an improved molecular structure may positively affect the photophysics of these molecules. This will be achieved by using a wide range of cutting-edge techniques, such as ultra-fast femtosecond transient absorption spectroscopy, and electron paramagnetic resonance, alongside with X-Ray diffraction measurements. This cross-examination will aim to complement the understanding of the photophysics with analysis of the molecular packing structure. This will give a broader understanding of the consequences of molecular design, and test the hypothesis that we can tailor molecular structure to harness singlet fission for renewable energy application and a cleaner environmental future.