Crack-tolerant materials for next-generation photovoltaics

简要描述研究背景，包括潜在影响：太阳能光伏发电（PV）目前占全球发电量的近4%，装机容量几乎呈指数级增长。由于安装过程中的误操作或机械应力而导致的光伏板裂纹是普遍存在的，但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面板中热点形成、加速效率下降和面板故障中的作用[1]。然而，裂纹对下一代光伏材料的影响尚未得到充分研究。多晶硫族化物和卤化物钙钛矿太阳能吸收剂是下一代光伏器件的有力候选者，将支持产能的可持续增长。有趣的是，我们最近的材料建模研究表明，这些材料中的许多材料本质上比硅更能抵抗键断裂（例如，在表面和晶界）[2，3]。因此，这些材料中的一些是否能够更耐受机械诱导的裂纹？该项目旨在通过预测材料建模和补充实验设备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PV材料（例如，Si、CdTe、Sb 2Se 3和卤化物钙钛矿），并深入了解它们对器件性能的影响。具体目标是：1）量化太阳能吸收材料的电子性质如何通过与原子尺度结构特征相关的裂纹形成而改变（例如断裂的键），2）针对不同的光伏技术，研究组件中裂纹的结构和性质（包括在封装失败的情况下，堆栈中不同层与环境之间的交互）并量化其对性能的影响，3）确定下一代光伏材料是最宽容的裂缝的形成。研究方法，包括新的知识或技术，在工程和物理科学，将被调查：密度泛函理论将被用来模拟太阳能吸收材料和扩展缺陷的性质，以便在原子水平上了解裂纹对材料的影响性能和性能[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，并扩展模拟的规模（时间和长度）。将对光伏器件进行补充实验研究（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/光致发光和热成像表征。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优先事项以及战略交付计划领域保持一致：物理和数学科学的发电站，前沿工程和技术和工程净零。任何公司或合作者参与：无[1] M.Dhimish等人，Sci. Rep. 11，23961（2021）[2] K.McKenna，ACS Energy Lett. 3，2663（2018）[3] K.McKenna，Adv. Electron. Mater. 2019 - 07 - 28 00：00：00

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)