Simple approach for the fabrication of PEDOT-coated Si nanowires.

Mingxuan Zhu,François Flory,Florence Boulc’H,Marielle Eyraud,Nadia Ait Ahmed,Judikael Le Rouzo,Claude Alfonso,Philippe Knauth

doi:10.3762/bjnano.6.65

Mingxuan Zhu, François Flory + Show 6 more

Open Access

https://doi.org/10.3762/bjnano.6.65

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Abstract

The synthesis of a conformal poly(3,4-ethylenedioxythiophene) (PEDOT) layer on Si nanowires was demonstrated using a pulsed electrodeposition technique. N-type Si nanowire (SiNWs) arrays were synthesized using an electroless metal-assisted chemical etching technique. The dependence of the SiNW reflection on the concentration of the AgNO3 solution was identified. A reflection of less than 2% over the entire visible spectral range was obtained for these structures, evidencing their excellent antireflective properties. The etched SiNWs nanostructures can be further modified by using a tapering technique, which further preserves the strong light trapping effect. P-type PEDOT was grown on these SiNWs using electrochemical methods. Since the polymerization reaction is a very fast process with regards to monomer diffusion along the SiNW, the conformal deposition by classical, fixed potential deposition was not favored. Instead, the core–shell heterojunction structure was finally achieved by a pulsed deposition method. An extremely large shunt resistance was exhibited and determined to be related to the diffusion conditions occurring during polymerization.

Highlights

Silicon nanowires (SiNWs) are a current, active research topic for many applications such as photovoltaics [1], lithium batteries [2], hydrogen storage [3] and optoelectronic devices [4] due to their unique properties with respect to visible light management [5,6,7]
Chemical vapor deposition (CVD) [10,11] and atomic layer deposition (ALD) [12] are methods that can be employed to obtain this type of nanostructured junction, they suffer from high cost
For this study, only those SiNWs that exhibit good optical performance which were suitable for PEDOT deposition were addressed

Summary

Introduction

Silicon nanowires (SiNWs) are a current, active research topic for many applications such as photovoltaics [1], lithium batteries [2], hydrogen storage [3] and optoelectronic devices [4] due to their unique properties with respect to visible light management [5,6,7]. Core–shell, radial p–n junctions can be realized by spin coating poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS) (a successful, commercial, conducting polymer) onto a SiNW array. This gave very promising results for photovoltaic cells based on this heterojunction, with a photon capture efficiency (PCE) of 6.72% [15]. A relatively low shunt resistance and a high saturation current are displayed by devices produced using the spin coating method. This is because the PEDOT:PSS only partially covers the SiNWs array, leaving most of the SiNW surface uncovered [16]. As well as morphology and composition of the samples, were determined using spectroscopy, current density–voltage curves, scanning electron and transmission electron microcopies, energy-dispersive X-ray analysis, and IR spectroscopy

Results and Discussion

Conclusion

Characterization methods