Nanometer–scale metal precipitates in multicrystalline silicon solar cells

• In this study, we have utilized characterization methods to identify the nature of metal impurityprecipitates in low performance regions of multicrystalline silicon solar cells. Specifically, we haveutilized synchrotron-based x-ray fluorescence and x-ray absorption spectromicroscopy to study theelemental and chemical nature of these impurity precipitates, respectively. We have detectednanometer-scale precipitates of Fe, Cr, Ni, Cu, and Au in multicrystalline silicon materials from avariety of solar cell manufacturers. Additionally, we have obtained a direct correlation between theimpurity precipitates and regions of low light-induced current, providing direct proof that metalimpurities play a significant role in the performance of multicrystalline silicon solar cells.Furthermore, we have identified the chemical state of iron precipitates in the low-performanceregions. These results indicate that the iron precipitates are in the form of oxide or silicatecompound. These compounds are highly stable and cannot be removed with standard siliconprocessing, indicating remediation efforts via impurity removal need to be improved. Futureimprovements to multicrystalline silicon solar cell performance can be best obtained by inhibitingoxygen and metal impurity introduction as well as modifying thermal treatments during crystalgrowth to avoid oxide or silicate formation.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

NATURVETENSKAP  -- Fysik -- Acceleratorfysik och instrumentering (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Accelerator Physics and Instrumentation (hsv//eng)

Nyckelord

multicrystalline silicon solar cell synchrotron XRF precipitate

Physics

Fysik

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