Se Inter-Diffusion Limits Absorber Layer Grain Growth in CdSe - CdTe Photovoltaics

Altamimi, T. F. S.; Leaver, J. F.; Durose, K.; Major, J. D.; Mendis, B. G.

Abstract

Diffusion of Se from the CdSe window layer into the CdTe absorber improves the short circuit current density by narrowing the band gap and increasing the carrier lifetime. Thicker CdSe layers, however, show a dramatic loss in photocurrent collection due to Se over-alloying. Electron microscopy investigations show that this decrease in performance is due to the formation of small grains (∼783 nm average diameter), which exhibit grain boundary porosity in the Se inter-diffusion region. The larger grain boundary area and void free surfaces give rise to higher levels of nonradiative recombination, and therefore, a lower photocurrent. It is proposed that the small grain size is due to a drag force exerted by segregated Se solute atoms on a moving grain boundary, while faster Se diffusion along the grain boundaries results in vacancy build up and porosity due to the Kirkendall effect. The results indicate that the device processing conditions must be carefully controlled such that the negative effects of Se alloying (i.e., smaller grains, Kirkendall voids) do not undermine its benefits. Published by the American Physical Society 2024

Citation

Altamimi, T. F. S., Leaver, J. F., Durose, K., Major, J. D., & Mendis, B. G. (2024). Se Inter-Diffusion Limits Absorber Layer Grain Growth in CdSe - CdTe Photovoltaics. PRX Energy, 3(2), Article 023002. https://doi.org/10.1103/prxenergy.3.023002

• Journal Article Type: Article
• Acceptance Date: Apr 26, 2024
• Online Publication Date: May 16, 2024
• Publication Date: May 16, 2024
• Deposit Date: Jun 15, 2024
• Publicly Available Date: Jun 17, 2024
• Journal: PRX Energy
• Print ISSN: 2768-5608
• Electronic ISSN: 2768-5608
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 3
• Issue: 2
• Article Number: 023002
• DOI: https://doi.org/10.1103/prxenergy.3.023002
• Public URL: https://durham-repository.worktribe.com/output/2484281