High efficiency and stability small molecule solar cells developed by bulk microstructure fine-tuning

Jie Min, Xuechen Jiao, Vito Sgobba, Bin Kan, Thomas Heumüller, Stefanie Rechberger, Erdmann Spiecker, Dirk M. Guldi, Xiangjian Wan, Yongsheng Chen, Harald Ade, Christoph J. Brabec

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44 Citations (Scopus)


Morphological control over the bulk heterojunction (BHJ) microstructure of a high-efficiency small molecule photovoltaic system composed of a quinquethiophene based molecule (DRCN5T) as electron donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) as electron acceptor is demonstrated using three different post-processing strategies, including thermal annealing (TA), solvent vapor annealing (SVA), and two-step annealing (TA-SVA) treatments. We systematically analyze the processing condition-microstructure-device property relationships, explore the corresponding morphology evolution and their effects on carrier transport and recombination dynamics in BHJs as well as understand the nature of phase-separation process resulting in light-induced degradation mechanisms. Within the investigated results, the causative relations between annealing sequence, photovoltaic parameters, morphology evolution and charge carrier dynamics are for the first time delineated. In addition, the observed trade-offs in device efficiency and stability with respect to the well-defined morphologies are highlighted. The in-depth picture of the bulk microstructure formation and its kinetic evolution as a function of the specific post-processing approaches is a valuable asset for the design of new photovoltaic materials and thin film nanoscale architectures that are more efficient and better aid future commercialization efforts.

Original languageEnglish
Pages (from-to)241-249
Number of pages9
JournalNano Energy
Publication statusPublished - 1 Oct 2016
Externally publishedYes


  • Annealing sequence
  • Blend microstructure
  • Charge carrier dynamics
  • Degradation mechanisms
  • Morphological control
  • Phase-separation

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