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Real-world applications of Moorfield products in science

PV Compositional Transformation Studies

Publication Title: Compositional Transformation and Impurity-Mediated Optical Transitions in Co-Evaporated Cu2AgBiI6 Thin Films for Photovoltaic Applications
Paper Abstract

Quaternary copper-silver-bismuth-iodide compounds represent a promising new class of wide-bandgap (2 eV) semiconductors for photovoltaic and photodetector applications. In this study, vapor phase co-evaporation is utilized to fabricate Cu2AgBiI6 thin films and photovoltaic devices. The findings show that the properties of vapor-deposited films are highly dependent upon processing temperature, exhibiting increased pinhole density and transforming into a mixture of quaternary, binary, and metallic phases depending on the post-deposition annealing temperature. This change in phase is accompanied by an enhancement in photoluminescence (PL) intensity and charge-carrier lifetime, along with the emergence of an additional absorption peak at high energy (≈3 eV). Generally, increased PL is a desirable property for a solar absorber material, but this change in PL is ascribed to the formation of CuI impurity domains, whose defect-mediated optical transition dominates the emission properties of the thin film. Via optical pump terahertz probe spectroscopy, it is revealed that CuI impurities hinder charge-carrier transport in Cu2AgBiI6 thin films. It is also revealed that the predominant performance limitation in Cu2AgBiI6 materials is the short electron-diffusion length. Overall, the findings pave the way for potential solutions to critical issues in copper-silver-bismuth-iodide materials and indicate strategies to develop environmentally compatible wide-bandgap semiconductors.

How Moorfield products helped:

Thermal Evaporation with co-deposition

Various materials were evaporated in the course of this exciting research using our MiniLab080 with thermal evaporation sources.

Open Access publication details:
Putland, B.W.J. et al. (2024) ‘Compositional Transformation and Impurity‐Mediated Optical Transitions in Co‐Evaporated Cu2 AgBiI6 Thin Films for Photovoltaic Applications’, Advanced Energy Materials, 14(8), p. 2303313. Available at: https://doi.org/10.1002/aenm.202303313.