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Title: Pathway for recovery of photo-degraded polymer solar cells by post degradation thermal anneal

The photo-degradation of polymer solar cells is a critical challenge preventing its commercial deployment. We experimentally fabricate organic solar cells and characterize their degradation under solar simulators in an environmental chamber under nitrogen flow, without exposure to oxygen and moisture. We have developed a thermally stable inverted organic solar cell architecture in which light induced degradation of device characteristics can be reversibly annealed to the pristine values. The stable inverted cells utilized MoO x layers that are thermally treated immediately after their deposition on the organic layer, and before metal cathode deposition. Organic solar cells that are photo-degraded in the presence of oxygen, however show irreversible degradation that cannot be thermally recovered. The decrease of organic solar cell characteristics correlates with increases in mid-gap electronic states, measured using capacitance spectroscopy and dark current. It is likely the photo-induced defect states caused by local H motion from the alkyl chains to the aromatic backbone, can be reversibly annealed at elevated temperatures after photo-degradation. Finally, our results provide a pathway for improving the stability of organic photovoltaics.
 [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [1] ;  [2]
  1. Iowa State Univ., Ames, IA (United States)
  2. (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0927-0248; PII: S0927024817300636
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Solar Energy Materials and Solar Cells
Additional Journal Information:
Journal Volume: 164; Journal Issue: C; Journal ID: ISSN 0927-0248
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; 14 SOLAR ENERGY; organic solar cells; photo degradation; Shockley Read Hall recombination; defect density; capacitance spectroscopy; thermal stability; stability
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1412605