Materials Discovery in Charge Transfer Complexes for Thermoelectricity

热电装置是一种电子芯片，可以将热量的差异转化为电能，反之亦然。大多数人从来没有听说过热电（TE）设备，因为他们很少使用。实用的TE设备可以产生绿色电力，减少制冷污染。由于室温热电材料要么太贵，要么效率太低，目前还无法实现这一目标。到2021年，将效率为1.4%的TE材料应用于英国所有热电厂产生的40摄氏度的废蒸汽，每年可产生5TWh的电力，足够200万英国家庭（占英国家庭总数的8%）使用，每年批发价值为9亿英镑（英国6月22日至6月23日的平均价格）。有机TE材料由于其原子丰度和低能量处理，有可能降低TE器件的成本。制造器件需要负极和正极（如电池的两端）TE材料。有机p型材料已经取得了很好的进展，但是n型材料非常稀少，性能较低，并且在空气中容易被氧化分解。最近发现了一类金属卤化物有机配合物，其一般结构为M(II)Br2（卤苯胺）2，具有高（2000-3900 S cm-1）的导电性和功率因数，其性能指标（1500 - 3700 W m1 K2）比PEDOT:PSS聚合物200 W m1 K2的研究基准高一个数量级。这个新家族的组成原子都是地球上丰富的，由Cu、Zn、Br、I、C和n组成。目前，加工溶剂是有毒的，但有可能开发出更安全、对环境危害更小的溶剂方法。至关重要的是，该家族在实验和理论上都报告了在空气和水中具有高稳定性的年时间尺度。并且最高工作温度在100 - 200℃之间，性能是现有最佳材料的五分之一到一半。这类材料作为TE材料尚未得到充分的探索，关于如何提高其性能的许多问题仍然存在。该项目将有助于开发其生产方法，发现家族中的新材料，并探索定制其性能的方法。早期的目标是通过真空干燥复制领先的研究成果。如果这种方法能够可靠地得到可以分析的薄膜，那么一个包含不同卤化物取代基和pi共轭体系的不同有机分子的文库将会被开发出来。这些实验将帮助我们了解分子对我们如何更好地制造材料的影响。如果数据生成是快速和可靠的，使用人工智能可以帮助我们改进材料。如果真空干燥技术不能提供可靠的高质量薄膜沉积，那么将研究替代干燥方法。热底物蒸发掉溶剂，使用一种溶剂，洗掉溶剂，但留下的材料到位。环境温度洗涤是有利的，因为它避免了热应力，并具有较低的能源需求。共溶剂技术可以更好地控制结晶。一旦薄膜被生产出来，将用光学显微镜、电子显微镜和轮廓术验证其均匀性和厚度。沉积膜的成分将由掠入射x射线衍射测定。以前的研究没有包括铸膜的结构测量，只包括机械化学和结晶产生的材料。对铸型胶片的分析将揭示任何差异。如果可能的话，这些材料将被浇铸到薄膜分析仪的氮化硅测量芯片上。该系统可以给出基本的热电特性。与传统测量相比，该系统的速度和高可靠性将减少每个样品的不确定度和时间。如果该系统不适合，将开发使用带有热蒸发导电轨道的硅载玻片进行4端测量的方法。

Thermoelectric devices are electronic chips that turn differences in heat into electricity and vice versa. Most people will have never heard of thermoelectric (TE) devices as they are used very little. Practical TE devices could generate green electricity and make refrigeration less polluting. This cant happen currently as room temperature thermoelectric materials are either too expensive or too inefficient. A 1.4% efficient TE material applied to the 40C waste steam generated by all UK thermal power plants in 2021 could have generated 5TWh of electricity per year, enough for 2 million, 8% of all, UK homes at a wholesale value of £900M per year (UK average price June 22 June 23). Organic TE materials are likely to reduce the cost of TE devices due to their atom abundance and low energy processing. Both negative and positive type (like the ends on a battery) TE materials are needed to make devices. Organic p-type materials have seen good progress, but n-types are much rarer, have lower performance, and are easily decomposed by oxidation in air. A recent discovery of a family of metal halide organic complexes with a generic structure M(II)Br2(Haloaniline)2 has reported high (2000-3900 S cm-1) electrical conductivity and power factors, a measure of TE performance (1500 3700 W m1 K2) an order of magnitude greater than the research benchmark of PEDOT:PSS polymer 200 W m1 K2.This new family's constituent atoms are all earth-abundant, comprised of Cu, Zn, Br, I, C and N.Currently, the processing solvent is toxic, but there is potential for developing safer and less environmentally harmful solvent methods. Crucially, this family reports high stability in air and water for year timescales experimentally and theoretically. And maximum operating temperatures between 100 - 200C and good performance one-fifth to half as good as the best materials available. This class of materials is underexplored as TE materials, and many questions about how to boost their performance remain. This project will help to develop methods for their production, discover new materials in the family and explore methods for tailoring their performance. The early goal will be to replicate the leading research results via vacuum drying. If this method reliably gives films that can be analysed, then a library of different organic molecules with different halide substituents and Pi-conjugated systems will be developed. These experiments will help us understand the molecule's effect on how we can make the materials better. If data generation is fast and reliable, the use of artificial intelligence could help us improve the materials. If the vacuum drying technique does not provide reliable deposition of high-quality films, then alternative drying methods will be investigated. Hot substrates to evaporate off the solvent, using a solvent that washes away the solvent but leaves the materials in place. Ambient temperature washing is favourable as it avoids thermal stress and has lower energy requirements. Cosolvent techniques may give finer control of the crystallisation. Once films are produced, they will be validated for homogeneity and thickness with Optical microscopy, Electron microscopy, and profilometry. The composition of the deposited films will be determined by grazing incidence x-ray diffraction. Previous studies have not included structural measurements of the cast films, only materials derived by mechanochemistry and crystallisation. Analysis of the cast film will reveal any differences. If possible, the materials will be cast onto the silicon nitride measurement chips of a thin film analyser. This system can give basic thermoelectric characterisation. This system's speed and high reliability will reduce uncertainty and time per sample compared to conventional measurements. If this system is unsuitable, methods will be developed using silica slides with thermally evaporated conductive tracks for 4 terminal measurements.