Applied Physics A

, 124:449 | Cite as

Realizing 11.3% efficiency in PffBT4T-2OD fullerene organic solar cells via superior charge extraction at interfaces

  • Cheng Xu
  • Matthew Wright
  • Naveen Kumar Elumalai
  • Md Arafat Mahmud
  • Dian Wang
  • Vinicius R. Gonçales
  • Mushfika Baishakhi Upama
  • Faiazul Haque
  • J. Justin Gooding
  • Ashraf Uddin


The influence of interface engineering on the performance and photovoltaic properties of the PffBT4T-2OD poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3′′′-di(2-octyldodecyl)-2,2′;5′,2″;5″,2′′′-quaterthiophen-5,5′′′-diy)] based polymer solar cells (PSCs) are investigated. Owing to the high crystallinity and processing parameter dependent morphology distribution of the PffBT4T-2OD polymer, the performance of the devices can vary significantly with power conversion efficiency (PCE) of around 10% has been reported via such morphology modification. In this work, we demonstrate the effect of trap state passivation at the electron transport layer (ETL)/Polymer interface on the performance of PffBT4T-2OD based PSCs. Aluminium doped ZnO (AZO) and pristine Zinc Oxide (ZnO) are employed as ETLs, which modified the polymer wettability and blend morphology. The interface engineered devices exhibited high PCE of over 11% with high Jsc of about 22.5 mA/cm2 which is about 19% higher than that of the conventional ZnO based devices. The reason behind such distinct enhancements is investigated using several material and device characterization methods including electrochemical impedance spectroscopy (EIS). The recombination resistance (Rrec) of the AZO based device is found to be 4.5 times higher than that of the ZnO devices. The enhanced photovoltaic parameters of the AZO based device are attributed to the superior charge transport characteristics in the ETL as well as at the ETL/polymer interface, enabling effective charge extraction at the respective electrodes with much lesser recombination. The mechanism and the processes behind such enhancements are also elaborated in detail.



The authors gratefully acknowledge the financial support provided by Future Solar Technologies Pty. Ltd. for this research work. The authors would also like to acknowledge the endless support from the staffs of Photovoltaic and Renewable Energy Engineering School, Electron Microscope Unit (EMU) and Solid State and Elemental Analysis Unit under Mark Wainwright Analytical Center, UNSW. J.J.G. acknowledges the ARC for the ARC Australian Laureate Fellowship (FL150100060).

Compliance with ethical standards

Conflict of interests

The author(s) declare no competing financial interests.

Supplementary material

339_2018_1867_MOESM1_ESM.docx (353 kb)
Supplementary material 1 (DOCX 353 KB)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Cheng Xu
    • 1
  • Matthew Wright
    • 1
  • Naveen Kumar Elumalai
    • 1
  • Md Arafat Mahmud
    • 1
  • Dian Wang
    • 1
  • Vinicius R. Gonçales
    • 2
  • Mushfika Baishakhi Upama
    • 1
  • Faiazul Haque
    • 1
  • J. Justin Gooding
    • 2
  • Ashraf Uddin
    • 1
  1. 1.School of Photovoltaic and Renewable Energy EngineeringUniversity of New South WalesSydneyAustralia
  2. 2.School of Chemistry and Australian Centre for NanoMedicineUniversity of New South WalesSydneyAustralia

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