Nanosphere Templated Continuous PEDOT:PSS Films with Low Percolation Threshold for Application in Efficient Polymer Solar Cells

Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
ACS Nano (Impact Factor: 12.88). 08/2012; 6(9):7902-9. DOI: 10.1021/nn3022926
Source: PubMed


Nanometer-sized monodisperse polystyrene nanospheres (PS NS) were designed as an opal template for the formation of three-dimensionally continuous poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films. The resultant films were successfully applied as the anode buffer layer (ABL) to produce highly efficient polymer solar cells (PSCs) with enhanced stability. The conductivity of the PS NS-PEDOT:PSS films was maintained up to ϕ(PS) = 0.75-0.80, indicating that the formation of continuous PEDOT:PSS films using PS NS templates was successful. To demonstrate the applicability of the PS NS-PEDOT:PSS film for organic electronics, the PS NS-PEDOT:PSS films were used as ABLs in two different PSCs: P3HT:PCBM and P3HT:OXCBA. The photovoltaic performances of both PSCs were maintained up to ϕ(PS) = 0.8. In particular, the power conversion efficiency of the P3HT:OXCBA PSC with a PS NS-PEDOT:PSS ABL (ϕ(PS) = 0.8) was greater than 5% and the air stability of the device was significantly enhanced.

Download full-text


Available from: Dong Jin Kang, Apr 28, 2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The randomly nanotextured back electrode provides a simple and efficient route for enhancing photocurrent in polymer solar cells (PSCs) by light trapping, which can increase light absorption within a finite thickness of the active layer. In this study, we incorporated mono-disperse 60 nm polystyrene nanoparticles (PS NPs) into a 50 nm thick poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) anode buffer layer (ABL) to create a randomly nanotextured back electrode with 10 nm height variations in inverted-type PSCs. The roughened interface between the PS NP-PEDOT:PSS ABL and the Ag electrode scatters light in the visible range, leading to efficient light trapping within the device and enhanced light absorption in the active layer. Inverted PSCs with randomly nanotextured electrodes (ϕ(NP) = 0.31) showed short-circuit current density (J(SC)) and power conversion efficiency (PCE) values that were 15% higher than those of control devices with flat electrodes. External quantum efficiency, reflectance, and optical light scattering as a function of ϕ(NP) were examined to determine the origin of the enhancement in J(SC) and PCE.
    Nanoscale 01/2013; 5(5). DOI:10.1039/c2nr33160h · 7.39 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Fullerene tris-adducts have the potential of achieving high open-circuit voltages (VOC) in bulk heterojunction (BHJ) polymer solar cells (PSCs), because their lowest unoccupied molecular orbital (LUMO) level is higher than those of fullerene mono- and bis-adducts. However, no successful examples of the use of fullerene tris-adducts as electron acceptors have been reported. Herein, we developed a ternary-blend approach for the use of fullerene tris-adducts to fully exploit the merit of their high LUMO level. The compound o-xylenyl C60 tris-adduct (OXCTA) was used as a ternary acceptor in the model system of poly(3-hexylthiophene) (P3HT) as the electron donor and the two soluble fullerene acceptors of OXCTA and fullerene mono-adduct (o-xyenyl C60 mono-adduct (OXCMA), phenyl C61-butyric acid methyl ester (PCBM) or indene-C60 mono-adduct (ICMA)). To explore the effect of OXCTA in ternary-blend PSC devices, the photovoltaic behavior of the device was investigated in terms of the weight fraction of OXCTA (WOXCTA). When WOXCTA is small (< 0.3), OXCTA can generate a synergistic bridging effect between P3HT and the fullerene mono-adduct, leading to simultaneous enhancement in both VOC and short-circuit current (JSC). For example, the ternary PSC device of P3HT:(OXCMA:OXCTA) with WOXCTA of 0.1 and 0.3 exhibited power-conversion efficiencies (PCEs) of 3.91% and 3.96%, respectively, which were significantly higher than the 3.61% provided by the P3HT:OXCMA device. Interestingly, for WOXCTA > 0.7, both VOC and PCE of the ternary-blend PSCs exhibited non-linear compositional dependence on WOXCTA. We noted that the non-linear compositional trend of P3HT:(OXCMA:OXCTA) was significantly different from that of P3HT:(OXCMA:o-xyenyl C60 bis-adduct (OXCBA)) ternary-blend PSC devices. The fundamental reasons for the differences between the photovoltaic trends of the two different ternary-blend systems were investigated systemically by comparing their optical, electrical, and morphological properties.
    ACS Applied Materials & Interfaces 04/2013; 5(10). DOI:10.1021/am400695e · 6.72 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Hollow microflower arrays (HMFAs) of poly(3,4-ethylenedioxythiophene) (PEDOT) with several two dimensional hollow nanopetals on each microflower are fabricated on a conducting glass by using ZnO microflower arrays as the template. Various charges are applied for the electrodeposition of the film of PEDOT-HMFAs, intending to investigate their effect on the film's morphology. A morphological variation is observed due to the swelling of PEDOT during the removal of the ZnO template. Cyclic voltammetry (CV) is used to optimize the charges for the deposition of the films of both a flat PEDOT and the PEDOT-HMFAs. Long-term stability of the films in an I−/I3− electrolyte is studied by CV. The PEDOT-HMFA film shows a better stability than those of the films of flat PEDOT and sputtered Pt. The PEDOT-HMFA film is employed as the catalytic material on the counter electrode (CE) of a dye-sensitized solar cell (DSSC). A power conversion efficiency of 7.20% is achieved, at 100 mW cm−2 for the DSSC with the film of PEDOT-HMFAs, which is much higher than that of the cell with the flat PEDOT (6.39%) and comparable to that of the cell with a sputtered Pt film on its CE (7.61%). Electrochemical impedance spectroscopy is used to substantiate the photovoltaic parameters. “Hemispherical diffusion of ions” occurs on each PEDOT hollow microflower of the CE with PEDOT-HMFAs in the DSSC, as against the linear diffusion occurring on the CE with flat PEDOT or sputtered Pt. This type of “hemispherical diffusion of ions” is explained to result in a smaller diffusion resistance of ions and thereby in a much higher fill factor for the DSSC using the CE with PEDOT-HMFAs.
    Journal of Materials Chemistry A 09/2013; 1(36):10693-10702. DOI:10.1039/C3TA10803A · 7.44 Impact Factor
Show more