Crack-tolerant materials for next-generation photovoltaics

研究背景的简要描述，包括潜在影响：太阳能光伏发电（pv）现在占全球发电量的近4%，装机容量几乎呈指数级增长。由于安装过程中操作不当或机械应力导致的光伏板裂纹是普遍存在的，但人们对影响光伏技术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键断裂在当前一代晶体硅板[1]中形成热点、加速效率下降和面板失效中的作用。然而，到目前为止，裂缝对未来下一代光伏材料的影响尚未被探索。多晶硫族化物和卤化物钙钛矿太阳能吸收器是下一代光伏设备的有力候选者，将支持容量的可持续增长。有趣的是，我们最近的材料模型研究表明，许多这些材料本质上比硅更坚固，抗键断裂（例如，在表面和晶界处）[2,3]。这些材料是否因此对机械引起的裂纹更有容忍度？该项目旨在通过预测材料建模和互补实验装置表征来研究这个问题，以帮助确定最有前途的耐裂纹PV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（如Si、CdTe、Sb2Se3和卤化物钙钛矿）电子性能的影响，并深入了解它们对器件性能的影响。具体目标是：1)量化与原子尺度结构特征（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)针对不同的光伏技术，研究组件中裂纹的结构和性能（包括封装失败时堆栈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，包括将被研究的工程和物理科学中的新知识或新技术：密度泛函理论将被用于模拟太阳能吸收材料和扩展缺陷的特性，以便提供原子层面的洞察力，了解裂纹对材料特性和性能的影响[2,3]。我们还将探索利用机器学习的潜力来加速材料和缺陷筛选方法，并扩大模拟的规模（时间和长度）。补充实验研究将在PV设备上进行（由合作者提供），使用机械弯曲来引发裂纹形成，以及结构，电气，电/光发光和热成像表征。与EPSRC的战略和研究领域保持一致：该研究与EPSRC在能源、物理科学和工程方面的研究重点以及战略交付计划领域保持一致：物理和数学科学强国、工程技术前沿和工程零净值。任何涉及的公司或合作者：无b[1] M.Dhimish等人，Sci。能源学报，2017,26 (2018),[3]K.McKenna, Adv.电子。材料7,2000908 （2021）

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)