Enhanced efficiency in dye sensitized solar cells with nanostructured Pt decorated multiwalled carbon nanotube based counter electrode

Nanostructured Pt decorated functionalized multiwalled carbon nanotubes (Pt/f-MWNTs) cast on fluorine doped tin oxide coated glass (FTO) is demonstrated as a novel counter electrode (CE) for dye sensitized solar cells (DSSCs). Pt particles (20 wt.%, size <5 nm) are uniformly decorated on f-MWNTs using a facile microwave assisted polyol reduction method. The DSSC fabricated with Pt/f-MWNTs CE (effective Pt loading ∼10 μg cm−2) exhibits an enhanced efficiency of ∼5.4% (under an illumination of AM 1.5 G, 100 mW cm−2), compared to ∼2.3% and 4.5% for f-MWNTs and Pt CE based reference DSSCs. The CEs are fabricated without using conventional binders using a simple doctor blade method. A new equivalent circuit is proposed to model the electrochemical impedance behavior of porous f-MWNTs based CE. On the other hand, the behavior Pt/f-MWNTs based electrode is similar to that of Pt nanoparticles but with higher catalytic activity. Cyclic voltammetry studies reveal that Pt/f-MWNTs counter electrode offers greater catalytic surface area and facilitates faster reaction at its surface.

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► Efficient counter electrode for dye sensitized solar cells (DSSC) is demonstrated.
► Simple and rapid decoration of Pt nanoparticles on multiwalled carbon nanotubes.
► Nano Pt-multiwalled carbon nanotubes electrode exhibits excellent catalytic activity.
► Catalytic activity investigated using impedance and cyclic voltammetry studies.
► New impedance model is proposed for porous carbon nanostructure based electrodes.