Toward Improved Lifetimes of Organic Solar Cells under Thermal Stress: Substrate-Dependent Morphological Stability of PCDTBT:PCBM Films and Devices

Zhe Li, Kar Ho Chiu, Raja Shahid Ashraf, Sarah Fearn, Rajeev Dattani, Him Cheng Wong, Ching Hong Tan, Jiaying Wu, João T. Cabral*, James R. Durrant

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Morphological stability is a key requirement for outdoor operation of organic solar cells. We demonstrate that morphological stability and lifetime of polymer/fullerene based solar cells under thermal stress depend strongly on the substrate interface on which the active layer is deposited. In particular, we find that the stability of benchmark PCDTBT/PCBM solar cells under modest thermal stress is substantially increased in inverted solar cells employing a ZnO substrate compared to conventional devices employing a PEDOT:PSS substrate. This improved stability is observed to correlate with PCBM nucleation at the 50nm scale, which is shown to be strongly influenced by different substrate interfaces. Employing this approach, we demonstrate remarkable thermal stability for inverted PCDTBT:PC 70 BM devices on ZnO substrates, with negligible (<2%) loss of power conversion efficiency over 160 h under 85 C thermal stress and minimal thermally induced burn-in effect. We thus conclude that inverted organic solar cells, in addition to showing improved environmental stability against ambient humidity exposure as widely reported previously, can also demonstrate enhanced morphological stability. As such we show that the choice of suitable substrate interfaces may be a key factor in achieving prolonged lifetimes for organic solar cells under thermal stress conditions.

Original languageEnglish (US)
Article number15149
JournalScientific Reports
Volume5
DOIs
StatePublished - Oct 15 2015

ASJC Scopus subject areas

  • General

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