Flexible ITO-free organic solar cells over 10% by employing drop-coated conductive PEDOT:PSS transparent anodes

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  • ReceivedDec 18, 2018
  • AcceptedJan 22, 2019
  • PublishedFeb 22, 2019


Highly conductive poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonic acid) (PEDOT:PSS) has been explored to fabricate flexible and stretchable conductors. Generally, PEDOT:PSS transparent anodes are prepared by spin-coating method. In this article, we adopt a method by dropping PEDOT:PSS aqueous solution on the PET plastic substrate to fabricate flexible electrodes. Compared with spin coating, drop-coating is simple and cost-effective with large-area fabrications. Through this method, we fabricated highly transparent conductive electrodes and systematically studied their electrical, optical, morphological and mechanical properties. With dimethyl sulfoxide/methanesulfonic acid (DMSO/MSA) treated PEDOT:PSS electrode, bendable devices based on non-fullerene system displayed an open-circuit voltage of 0.925 V, a fill factor of 70.74%, and a high power conversion efficiency (PCE) of 10.23% under 100 mW cm−2 illumination, which retained over 80% of the initial PCE value after 1000 bending cycles. Based on the findings, drop-coated PEDOT:PSS electrodes exhibited high suitability for the development of large-area and high-efficiency printed solar cell modules in the future.

Funded by

the National Key R&D Program of China(2017YFE0106000)

the National Natural Science Foundation of China(51773212,21574144,21674123,61705240)

Zhejiang Provincial Natural Science Foundation of China(LR16B040002)

Ningbo Municipal Science and Technology Innovative Research Team(2015B11002,2016B10005)

CAS Interdisciplinary Innovation Team

CAS Key Project of Frontier Science Research(QYZDBSSW-SYS030)

and CAS Key Project of International Cooperation(174433KYSB20160065)


This work was supported by the National Key R&D Program of China (2017YFE0106000), the National Natural Science Foundation of China (51773212, 21574144, 21674123, 61705240), Zhejiang Provincial Natural Science Foundation of China (LR16B040002), Ningbo Municipal Science and Technology Innovative Research Team (2015B11002, 2016B10005), CAS Interdisciplinary Innovation Team, CAS Key Project of Frontier Science Research (QYZDBSSW-SYS030), and CAS Key Project of International Cooperation (174433KYSB20160065).

Interest statement

The authors declare that they have no conflict of interest.


Supporting Information

The supporting information is available online at http://chem.scichina.com and http://link.springer.com/journal/11426. The supporting materials are published as submitted, without typesetting or editing. The responsibility for scientific accuracy and content remains entirely with the authors.


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  • Figure 1

    Transmission spectra of the drop-coated PEDOT:PSS films on glass substrates (color online).

  • Scheme 1

    Schematic illustration for the PEDOT:PSS FTEs via drop coating techniques (color online).

  • Figure 2

    Atomic force microscope phase images of PEDOT:PSS films on glass substrates. (a) Pristine films; (b) MSA-treated films; (c) DMSO-treated films; (d) DMSO/MSA-treated films; (e) EG-treated films; (f) EG/MSA-treated films. Scale bar: 2 µm×2 µm (color online).

  • Figure 3

    XPS S (2p) spectra of pristine film and DMSO/MSA-treated PEDOT:PSS film (color online).

  • Figure 4

    (a) Schematic diagram of the bendable OSC devices. (b) J-V curves of all flexible OSC devices with the drop-coated PEDOT:PSS FTEs. (c) J-V curves of flexible OSC devices with the spin-coated PEDOT:PSS film treated by DMSO/MSA and the drop-coated PEDOT:PSS film treated by DMSO/MSA. (d) Decays of normalized PCEs of flexible devices as a function of the bending times (color online).

  • Table 1   FoM parameters of PEDOT:PSS films


    Transmission at 550 nm

























  • Table 2   Photovoltaic performance of rigid (glass substrate) and flexible (PET substrate) devices based on PEDOT:PSS or ITO and deposited through spin-coating or drop-coating method


    Voc (V)


    FF (%)

    PCE (ave.) (%)

    Rsq(Ω cm2)

    ITO (110 nm) (Glass)c)




    11.06 (10.95)


    DMSO/MSA (PET)c)




    10.45 (10.22)


    DMSO/MSA (PET)b)




    10.23 (10.08)


    EG/MSA (PET)b)




    9.63 (9.58)


    MSA (PET)b)




    9.32 (9.19)


    DMSO (PET)b)




    8.79 (8.73)


    EG (PET)b)




    8.70 (8.65)


    ITO (185 nm) (PET)c)




    7.84 (7.62)


    All devices with 0.04 cm2 effective area; b) drop-coated films; c) spin-coated.

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