Intermolecular Charge Transport: A Novel Design Paradigm

预计可再生能源将在实现我们的目标方面发挥重要作用，即到2050年结束英国对全球变暖的贡献。新兴的薄膜技术，如钙钛矿太阳能电池（PSC），正在扩大光伏（pv）的应用范围，超出传统硅基pv的有效能力。这些设备能够在弱光条件下工作，并且可以作为廉价的轻量化柔性设备轻松打印，使其适合集成在室内和便携式系统中。2 .已经证明2PSCs的效率高达25.2%，硅基串联电池的效率为28%它们利用丰富、低成本的起始材料，并且比传统的硅太阳能电池生产能耗更低然而，一个关键的挑战仍然是“孔”传输材料（HTM），它在控制这些设备的整体性能和成本方面起着重要作用光线照射到钙钛矿吸收体上会使其电子激发到更高的能级，留下一个带正电的“空穴”。HTM然后将这些孔从吸收器移向电极，从而使电流流过器件。其中一个问题是电荷重组，这限制了效率。此外，最先进的HTMs，如spiro-OMeTAD，价格昂贵且难以合成。新型HTMs的开发成本仅为传统材料的一小部分，采用简单的化学方法它们的合成可以在环境条件下进行，不需要金属催化，简单的分离技术可以提供高产量和高纯度的产品。通过组合不同的核心和侧组，可以创建HTM库，调整结构以优化其性能。然而，这些新材料的性能仍然不如最先进的HTMs。本项目旨在研究热媒对分子间电荷输运的影响。通过理论和实验相结合的方法，我们希望了解使用凝聚化学合成的新型材料的改进电荷输运性质，在主干中具有中断共轭将进行理论研究，以调查已知HTMs的性质，包括电导率和载流子迁移率。基于我们的发现，我们的目标是设计和合成将被测试的改进材料，无论是作为“孔”设备还是在psc内。将进行已知HTMs的计算研究，研究中性和带电物质以及从基态到激发态的转变。这些结果将用于深入了解影响性能的性质，如载流子迁移率、填料和溶解度。我们的发现将指导具有改进电荷输运特性的新型HTMs的设计。分子将被合成，扩大我们的分子范围，使用缩合化学合成，最初在主链上有断裂的偶联。性能相关的光电子和分子的物理特性，将在“孔”设计和psc内进行测试。分子性质将通过紫外可见吸收光谱和循环伏安法实验计算。将测量HTMs的电导率和载流子迁移率。最后，对热媒膜的热转变、稳定性和形貌进行了分析。具有适当性质的HTMs将用于制造PSCs，并将研究这些器件的结构和PV特性。使用迭代方法，我们的结果将用于优化设计过程，并获得性能更好的html。

Renewable energy is expected to play a major role in reaching our target to end the UK's contribution to global warming by the year 2050.1 Emerging thin-film technologies, such as perovskite solar cells (PSC), are widening the scope of photovoltaics (PVs) to applications beyond the effective capabilities of conventional silicon based PVs. These devices are able to operate under low light conditions and can be printed easily as cheap lightweight-flexible devices, making them suitable for integration within indoor and portable systems.2PSCs with high efficiencies of 25.2%, and 28% within silicon-based tandem cells, have been already demonstrated.3 They make use of abundant, low-cost starting materials and are less energy intensive to produce than conventional silicon solar cells.4 However, a key challenge remains the 'hole' transport material (HTM) which plays a major role in controlling the overall performance and cost of these devices.4 Light hitting the perovskite absorber causes excites its electrons to a higher energy level, leaving behind a positively charged 'hole'. The HTM then shuttles these holes away from the absorber and toward the electrode allowing a current to flow through the device. One problem is charge recombination, which limits efficiency. In addition, state-of-the-art HTMs, such as spiro-OMeTAD, are expensive and difficult to synthesise.4Novel HTMs, have been developed at a fraction of the cost of conventional materials, employing simple chemistry.4,5,6 Their synthesis can be carried out under ambient conditions,without the need for metal catalysis, and trivial isolation techniques furnish products in high yields and purities. By combining different core and side groups, HTM libraries can be created, tuning structures to optimise their performance. However, these novel materials still do not outperform state-of-the-art HTMs.This project aims to investigate intermolecular charge transport affected by the HTM. By combining theoretical and experimental approaches, we are looking to understand the improved charge transport properties of novel materials, synthesised using condensation chemistry, with disrupted conjugation in the backbone.4 Theoretical studies will be carried out to investigate the properties of known HTMs, including conductivity and charge carrier mobility. Based on our findings we aim to design and synthesise improved materials which will be tested, both as 'hole'-only devices and within PSCs.Computational studies of known HTMs will be conducted, studying the neutral and charged species as well as transitions from the ground state to the excited state. These results will be used to gain an insight into properties, such as charge carrier mobility, packing and solubility, that effect performance. Our findings will guide the design of novel HTMs with improved charge transport properties. Molecules will be synthesised that expand on our range of molecules, synthesised using condensation chemistry, initially with disrupted conjugation in the backbone.Performance-related optoelectronic and physical properties of the molecules, will be tested both in 'hole'-only devises and within PSCs. Molecular properties will be calculated from UV-visible absorption spectra and cyclic voltammetry experiments. The conductivity and charge-carrier mobilities of HTMs will be measured. Finally, thermal transitions, stability and profile of HTM films will be analysed. HTMs with the appropriate properties will be used to fabricate PSCs and the structure and PV characteristics of these devices will be studied. Using an iterative approach, our results will be used to optimise the design process and arrive at better performing HTMs.