Crack-tolerant materials for next-generation photovoltaics

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)