Crack-tolerant materials for next-generation photovoltaics

对研究背景的简要描述，包括潜在影响：太阳能光伏(PV)目前占全球发电量的近4%，装机容量几乎呈指数级增长。由于安装过程中的处理不当或机械应力导致的光伏电池板裂缝是普遍存在的问题，但人们对影响光伏技术的性能和可持续性的问题知之甚少。最近，我们强调了裂纹和相关的键断裂在当前一代晶体硅板的热点形成、加速效率下降和面板失效中的作用[1]。然而，到目前为止，未来的下一代光伏材料中裂纹的影响还没有被开发出来。多晶硫化物和卤化物钙钛矿太阳能吸收材料是下一代光伏器件的有力候选者，将支持可持续的产能增长。有趣的是，我们最近的材料模拟研究表明，这些材料中的许多本质上比硅[2，3]更能抵抗键的断裂(例如，在表面和晶界)。因此，这些材料中的一些会不会对机械引起的裂缝有更好的容忍度？本项目旨在通过预测材料模型和补充实验器件特性来研究这一问题，以帮助确定最有前途的抗裂光伏材料。目的和目标：我们的目标是研究裂纹形成对一系列光伏材料(例如，Si、CdTe、Sb2Se3和卤化物钙钛矿)的电子性质的影响，并深入了解它们对器件性能的影响。具体目标是1)量化与原子级结构特征(如断键)相关的裂纹形成如何改变太阳能吸收材料的电子性能，2)对于不同的光伏技术，调查模块中裂纹的结构和性质(包括封装失败时堆叠中不同层与环境之间的相互作用)，并量化它们对性能的影响，3)确定最能容忍裂纹形成的下一代光伏材料。研究方法，包括将要研究的工程和物理科学方面的新知识或新技术：将使用密度泛函理论对太阳能吸收材料的性能和扩展的缺陷进行建模，以便提供原子水平的洞察，了解裂纹对材料性能和性能的影响[2，3]。我们还将探索使用机器学习潜力来加速材料和缺陷筛选方法，并延长模拟的规模(时间和长度)。将对光伏设备(由合作者提供)进行补充的实验调查(由合作者提供)，使用机械弯曲来启动裂纹形成以及结构、电气、电/光致发光和热成像特性。与EPSRC的战略和研究领域保持一致：研究符合EPSRC在能源、物理科学和工程以及战略交付计划领域的优先事项：物理和数学科学强国、工程和技术前沿以及工程净零点。任何参与的公司或合作者：None[1]M.Dhimish等人，Sci。代表11,23961(2021年)[2]K·麦肯纳，美国能源通讯。3,2663(2018)[3]K.McKenna，Adv.Electron.马特。7,2000908(2021年)

Brief description of the context of the research including potential impact:Solar photovoltaics (PVs) now account for close to 4% of global electricity generation, with installed capacity growing almost exponentially. Cracks in PV panels caused by mishandling during installation or mechanical stress are ubiquitous but poorly understood problems impacting the performance and sustainability of PV technology. Recently we have highlighted the role of cracks and associated bond breaking in the formation of hotspots, accelerated efficiency degradation and panel failure in current-generation crystalline silicon panels [1]. However, the effects of cracks in prospective next-generation PV materials are so far unexplored.Polycrystalline chalcogenide and halide perovskite solar absorbers are strong candidates for next-generation PV devices that will support the sustainable growth of capacity. Intriguingly, our recent materials modelling investigations have shown that many of these materials are intrinsically more robust against the rupture of bonds (for example, at surfaces and grain boundaries) than silicon [2,3]. Could some of these materials therefore be more tolerant to mechanically induced cracks? This project aims to investigate this question through predictive materials modelling and complementary experimental device characterisation to help identify the most promising crack-tolerant PV materials.Aims and objectives:We aim to investigate the effect of crack formation on the electronic properties of a range of PV materials (e.g., Si, CdTe, Sb2Se3 and halide perovskites) and provide insight into their impact on device performance. The specific objectives are to 1) Quantify how the electronic properties of solar absorber materials are modified by crack formation correlating with atomic scale structural features (such as broken bonds), 2) For different PV technologies investigate the structure and properties of cracks in modules (including the interaction between different layers in the stack and the environment in case the encapsulation fails) and quantify their effect on performance, 3) Identify next-generation PV materials that are most tolerant to the formation of cracks.The research methodology, including new knowledge or techniques in engineering and physical sciences that will be investigated:Density functional theory will be employed to model the properties of solar absorber materials and extended defects in order to provide atomistic level insight into the effect of cracks on material properties and performance [2,3]. We will also explore the use of machine learning potentials to both accelerate materials and defect screening approaches and to extend the scale (both time and length) of simulations. Complementary experimental investigations will be carried out on PV devices (provided by collaborators) using mechanical bending to initiate crack formation together with structural, electrical, electro/photo-luminescence, and thermal-imaging characterisation.Alignment to EPSRC's strategies and research areas:The research aligns to EPSRC research priorities in Energy, Physical sciences and Engineering and the strategic delivery plan areas: Physical and mathematical sciences powerhouse, Frontiers in engineering and technology and Engineering net zero.Any companies or collaborators involved:None[1] M.Dhimish et al., Sci. Rep. 11, 23961 (2021)[2] K.McKenna, ACS Energy Lett. 3, 2663 (2018)[3] K.McKenna, Adv. Electron. Mater. 7, 2000908 (2021)