Surface Engineering Solid State Dye-Sensitized Solar Cells

染料敏化太阳能电池(DSC)可以被描述为一种“人工光合作用”，因为在这两种情况下，光都是由色素(光合作用中的叶绿素或DSC中的合成染料)获取的。这很有趣，因为光合作用的效率约为5%，因为入射光能(即光子)被捕获到光合作用副产品中的能量。尽管效率明显很低，但光合作用支持地球生物圈已有亿万年之久。其中一个原因是每天都有大量的阳光到达地球表面。据估计，尽管全球人口使用大量能源，但这一数字仍比全球年能源消耗量高出约6000倍。考虑到太阳还将持续数十亿年，阳光比目前可用的任何其他能源都要丰富得多。在这种情况下，如果我们使用10%的能效光伏，只使用地球表面的0.2%就可以满足能源需求，同时在生产过程中只释放微量温室气体，在运行过程中不排放任何温室气体。这将减缓与化石燃料相关的气候变化的加速步伐。尽管最近光伏发电大幅增加(英国约11千兆瓦，全球约225千兆瓦)，但这仍只占当前能源需求的一小部分；问题是为什么？晶硅光伏目前在市场上占主导地位(约90%)，但重量较大，硬度较高，通常采用批处理工艺制成有限的产品形式(长方形、封装式、玻璃板)。尽管这些产品已经上市多年，但它们仍然固定在现有屋顶上的框架上，电线经常穿过开放的屋顶空间。这项研究将开发可以通过连续(卷到卷，R2R)处理来打印的PV。由于R2R比批处理更快，它将降低制造成本，但增加了可生产的产品数量。R2R产品也可以制作成任何长度或宽度，这将彻底改变光伏产品的形式。也许最重要的是，通过改变光伏衬底，这将使光伏能够完全集成到屋顶/墙板或窗户中。这将极大地减少安装和平衡系统成本(即光伏面板安装系统、DC/AC电源逆变器、布线、开关、电池存储)，这些成本几乎占大多数光伏安装成本的一半。DSC技术已经投入商业生产(www.gcell.co.uk)，并且已经知道适用于R2R处理。此外，DSC原料无毒、储量丰富。虽然DSC器件的寿命已被报告为25,000小时(相当于~25年的运行)，但所使用的液体电解液可能会泄漏，并且对某些金属具有腐蚀性，这增加了基板成本。这项提议将这种液体电解液交换为固体电荷载体，以制造固态DSC(SsDSC)器件，以避免这些问题。虽然以前已经制作了单层DSC，但它的结构一直很难控制，因为这涉及到在多孔膜中的多孔金属氧化物颗粒上沉积两层不同的薄层化学物质。由此产生的不一致的层覆盖会导致能量损失，从而限制了器件的效率。为了克服这一点，我们将使用自组装分子和计算机模拟来探索表面化学/结构，以加快研究速度。因此，我们将设计染料和充电载体，使其行为像“停车场中的自动泊车”，并在安装到位之前移动到正确的位置。然后，通过控制自组装过程，我们将在设备中添加多种染料以增加光采集率，以提高设备效率以减少回报时间，即客户在能源账单上节省了足够的钱来支付系统购买成本的时间。通过将计算机建模和实验相结合，我们将通过减少所需的材料修改周期，将设计和制造时间缩短多达10倍。

Dye-sensitized solar cells (DSC) can be described as a form of "artificial photosynthesis" because, in both cases, light is harvested by a pigment (chlorophyll in photosynthesis or a synthetic dye in DSC). This is interesting because photosynthesis is ~5% efficient in terms of the incident light energy (i.e. photons) captured to the energy in the photosynthetic by-products. Despite this apparently low efficiency, photosynthesis has supported the planet's biosphere for aeons. One reason for this is the huge amount of sunlight which reaches the Earth's surface every day. This has been estimated to be ~6,000x more than annual global energy consumption despite the growing global population using huge amounts of energy. Given that the sun will last for billions more years, sunlight is vastly more abundant than any other energy source currently available. In this context, if we use 10% efficient PV, using only 0.2% of the Earth's surface would meet energy demands whilst releasing only trace greenhouse gases during production and none during operation. This will slow the accelerating pace of fossil fuel related climate change.Whilst PV uptake has increased hugely recently (~11GW in UK and >225GW globally), this still represents a tiny fraction of current energy demand; the question is why? Crystalline Si PV currently dominates the market (~90%) but is heavy, rigid and is usually made from batch-like processes into limited product forms (rectangular, encapsulated, glass panels). And despite these products being available for many years, they are still bolted onto frames attached onto existing roofs with wires often running across open roof-space. They do not fit, they are a "bolt-on" solution.This research will develop PV which can be printed by continuous (roll-to-roll, R2R) processing. Because R2R is faster than batch processing, it will reduce manufacturing costs but increase the amount of product which can be made. R2R product can also be made to any length or width which will revolutionise PV product form. Perhaps most importantly, by varying the PV substrate, this will enable PV to be fully integrated into roof/wall panels or windows. This will drastically reduce installation and balance of systems costs (i.e. PV panel mounting system, DC/AC power inverters, wiring, switches, battery storage) which make up almost half of the cost of most PV installations. DSC technology is already in commercial production (www.gcell.co.uk) and is already known to be suitable for R2R processing. In addition, DSC raw materials are non-toxic and abundant. Whilst DSC device lifetimes >25,000h have been reported (equivalent to ~25y operation), the liquid electrolytes used can leak and are corrosive to some metals which increases substrate costs. This proposal will exchange this liquid electrolyte for a solid, charge carrier to make solid state DSC (ssDSC) devices to avoid these issues. Whilst ssDSC have been made before, it has been difficult to control their construction because this involves depositing 2 thin layers of different chemicals onto porous metal oxide particles in a porous film. The resulting inconsistent layer coverage causes energy losses which limits device efficiency. To overcome this, we will use self-assembling molecules and computer modelling to explore surface chemistry/structure to speed-up the research. Thus, we will design dyes and charge carriers to behave like "self-parking cars in a car park" and move to the correct position before fixing themselves in place. Then, by controlling the self-assembly process, we will add multiple dyes into the device to increase light harvesting to improve device efficiency to reduce pay-back times; i.e. the time when the customer has saved enough money on their energy bills to pay off the system purchase costs. By combining computer modelling and experiment, we will cut design to manufacture times up to 10-fold by reducing the number of material modification cycles required.