Local nm-Scale Imaging of Electrical Contact for Series Resistance Degradation of Silicon Solar Cells

Chun-Sheng Jiang, Steven Johnston, E. Gaulding, Michael Deceglie, R. Flottemesch, C. Xiao, Helio Moutinho, Dana Sulas-Kern, John Mangum, Mowafak Al-Jassim, Ingrid Repins

Research output: Contribution to conferencePaperpeer-review

Abstract

We report on an electrical conduction mechanism for series resistance (Rs) degradation observed in a utility scale solar farm by nm-scale imaging of the local resistance at the Ag/Si interface of c-Si front metallization. Scanning spreading resistance microscopy imaging revealed that the number of point or small area electrical contacts decreased in a degraded cell compared to an unaffected cell, demonstrating the direct root cause of the Rs degradation. The degraded cell shows both a morphological and chemical difference in the screen-printed finger contact compared to the unaffected cell, which likely caused the degradation during the long-term field service. The reduction in electrical contact is likely caused by a structural change: The Ag particles in contact with the Si cell aggregate into bulk Ag, and a highly resistive ceramic oxide is formed in a 'belt' shape at the Ag/Si interface. This resistive belt with a thickness of sim 1 mu mathrm{m} blocks the current conduction from cell emitter to the Ag grid. Our results demonstrate an example of the multi-scale characterization approach for understanding degradation mechanisms in photovoltaics.

Original languageAmerican English
Pages872-874
Number of pages3
DOIs
StatePublished - 2022
Event49th IEEE Photovoltaics Specialists Conference, PVSC 2022 - Philadelphia, United States
Duration: 5 Jun 202210 Jun 2022

Conference

Conference49th IEEE Photovoltaics Specialists Conference, PVSC 2022
Country/TerritoryUnited States
CityPhiladelphia
Period5/06/2210/06/22

Bibliographical note

See NREL/JA-5K00-83107 for paper as published in IEEE Journal of Photovoltaics

NREL Publication Number

  • NREL/CP-5K00-85047

Keywords

  • c-Si solar cell
  • front metallization
  • nm-scale imaging
  • scanning spreading resistance microscopy (SSRM)
  • series resistance degradation

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