Title: Imaging CdCl₂ defect passivation and formation in polycrystalline CdTe films by cathodoluminescence

Abstract

Polycrystalline thin-film solar cells are attractive for low-cost photovoltaics, but their efficiencies are hindered by material quality issues. State-of-the-art CdTe solar cells use CdCl₂ annealing treatments whose effects are still being discovered at a fundamental level. Here, a series of CdTe samples with different annealing temperatures is investigated with high-resolution hyperspectral cathodoluminescence mapping measured at both room temperature and low temperature on the same microscopic areas. A statistical analysis over a large number of grains is combined with a local analysis at grain boundaries. The results elucidate the dynamic interplay between grain boundary and intragrain defect passivation and formation, in the midst of grain growth. The CdCl₂ annealing initially contributes to an increase of the grain size and the passivation of both grain boundaries and grain interiors, increasing the overall luminescence and diffusion length. For higher annealing temperatures, a further increase of grain size is counterbalanced by the rise of bulk defects. The results illustrate the tradeoffs that lead to an optimal annealing temperature, as well as new methods for understanding defect passivation and creation in thin film solar cells.

Authors:

Biduad, Thomas  ^[1];

• Search DOE PAGES for author "Biduad, Thomas"
• Search DOE PAGES for ORCID "0000-0003-2166-6154"

Moseley, John ^[2]; Amarasinghe, Mahisha ^[3]; Al-Jassim, Mowafak ^[2]; Metzger, Wyatt K. ^[2]; Collin, Stéphane  ^[1]

• Search DOE PAGES for author "Collin, Stéphane"
• Search DOE PAGES for ORCID "0000-0001-6176-1653"

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+ Show Author Affiliations

1. Alternative Energies and Atomic Energy Commission (CEA), Saclay (France)
2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
3. National Renewable Energy Lab. (NREL), Golden, CO (United States); Univ. of Illinois, Chicago, IL (United States)

Publication Date:

Thu Jun 03 00:00:00 EDT 2021

Research Org.:

National Renewable Energy Lab. (NREL), Golden, CO (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:

1787552

Report Number(s):

NREL/JA-5K00-77479
Journal ID: ISSN 2475-9953; MainId:27415;UUID:fc73e88c-e6c0-4d6e-bde8-4399e7e3e8f8;MainAdminID:24525; TRN: US2212327

Grant/Contract Number:  

AC36-08GO28308

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review Materials

Additional Journal Information:

Journal Volume: 5; Journal Issue: 6; Journal ID: ISSN 2475-9953

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

14 SOLAR ENERGY; thin film solar cells; cathodoluminescence; grain boundaries; passivation; defects