Comparing non-fullerene acceptors with fullerene in polymer solar cells: a case study with FTAZ and PyCNTAZ

Nicole Bauer, Qianqian Zhang, Jingbo Zhao, Long Ye, Joo Hyun Kim, Iordania Constantinou, Liang Yan, Franky So, Harald Ade, He Yan, Wei You

Research output: Contribution to journalArticle

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Abstract

Non-fullerene acceptors (NFAs) are becoming a serious contender to fullerene-based electron acceptors in organic photovoltaics, due to their structural versatility and easily tunable optical and electronic properties. However, NFA-based solar cells often have a decreased short-circuit current (Jsc) and fill factor (FF) compared to their fullerene-based counterparts. Here, we investigate the fundamental causes of this decrease in the performance of solar cells using a non-fullerene acceptor (SF-PDI2) paired with two polymer donors, FTAZ and PyCNTAZ, compared with their fullerene-based counterparts. Through a number of experimental techniques and morphological studies, we show that the SF-PDI2-based solar cells suffer from insufficient charge generation, transport, and collection when compared with the PCBM-based solar cells. The SF-PDI2-based solar cells show increased bimolecular recombination, which, together with other recombination loss mechanisms in these cells, causes a significant decrease in their Jsc and FF. Notably, the less pure domains, low electron mobility (on the order of 10−5 cm2 V−1 s−1), and imbalanced mobility (in regard to the hole mobility) further explain the low FF. On the other hand, the higher open-circuit voltage (Voc) in the SF-PDI2 devices is mainly due to the increase in the CT state energy. It is worth mentioning that the PyCNTAZ-based devices show an ultralow charge separation energy (ΔECS), close to 0 eV. Our results demonstrate that further increasing the mobility (both of electrons and holes) in these NFA-based solar cells would be a viable approach to further enhance the efficiency of these new types of solar cells, ideally, without losing the high Voc of such cells.

LanguageEnglish (US)
Pages4886-4893
Number of pages8
JournalJournal of Materials Chemistry A
Volume5
Issue number10
DOIs
StatePublished - Jan 1 2017

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Fullerenes
Solar cells
Hole mobility
Electrons
Electron mobility
Open circuit voltage
Polymer solar cells
Electronic properties
Short circuit currents
Electron energy levels
Polymers
Optical properties

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

Cite this

Comparing non-fullerene acceptors with fullerene in polymer solar cells : a case study with FTAZ and PyCNTAZ. / Bauer, Nicole; Zhang, Qianqian; Zhao, Jingbo; Ye, Long; Kim, Joo Hyun; Constantinou, Iordania; Yan, Liang; So, Franky; Ade, Harald; Yan, He; You, Wei.

In: Journal of Materials Chemistry A, Vol. 5, No. 10, 01.01.2017, p. 4886-4893.

Research output: Contribution to journalArticle

Bauer, N, Zhang, Q, Zhao, J, Ye, L, Kim, JH, Constantinou, I, Yan, L, So, F, Ade, H, Yan, H & You, W 2017, 'Comparing non-fullerene acceptors with fullerene in polymer solar cells: a case study with FTAZ and PyCNTAZ' Journal of Materials Chemistry A, vol. 5, no. 10, pp. 4886-4893. https://doi.org/10.1039/c6ta10450a
Bauer, Nicole ; Zhang, Qianqian ; Zhao, Jingbo ; Ye, Long ; Kim, Joo Hyun ; Constantinou, Iordania ; Yan, Liang ; So, Franky ; Ade, Harald ; Yan, He ; You, Wei. / Comparing non-fullerene acceptors with fullerene in polymer solar cells : a case study with FTAZ and PyCNTAZ. In: Journal of Materials Chemistry A. 2017 ; Vol. 5, No. 10. pp. 4886-4893.
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