Enhanced Charge Selectivity via Anodic-C60Layer Reduces Nonradiative Losses in Organic Solar Cells

Manasi Pranav, Johannes Benduhn, Mathias Nyman, Seyed Mehrdad Hosseini, Jonas Kublitski, Safa Shoaee, Dieter Neher, Karl Leo, Donato Spoltore

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Interfacial layers in conjunction with suitable charge-transport layers can significantly improve the performance of optoelectronic devices by facilitating efficient charge carrier injection and extraction. This work uses a neat C60 interlayer on the anode to experimentally reveal that surface recombination is a significant contributor to nonradiative recombination losses in organic solar cells. These losses are shown to proportionally increase with the extent of contact between donor molecules in the photoactive layer and a molybdenum oxide (MoO3) hole extraction layer, proven by calculating voltage losses in low- and high-donor-content bulk heterojunction device architectures. Using a novel in-device determination of the built-in voltage, the suppression of surface recombination, due to the insertion of a thin anodic-C60 interlayer on MoO3, is attributed to an enhanced built-in potential. The increased built-in voltage reduces the presence of minority charge carriers at the electrodes - a new perspective on the principle of selective charge extraction layers. The benefit to device efficiency is limited by a critical interlayer thickness, which depends on the donor material in bilayer devices. Given the high popularity of MoO3 as an efficient hole extraction and injection layer and the increasingly popular discussion on interfacial phenomena in organic optoelectronic devices, these findings are relevant to and address different branches of organic electronics, providing insights for future device design.

Original languageEnglish
JournalACS Applied Materials and Interfaces
DOIs
Publication statusAccepted/In press - 2021
MoE publication typeA1 Journal article-refereed

Keywords

  • charge selectivity
  • interfacial layers
  • molybdenum oxide
  • nonradiative losses
  • organic solar cells

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