Papers by Author: M. Raghavender

Abstract: A low-cost platinum (Pt) free electrocatalyst of NiSe₂ and Ni_0.9X_0.1Se₂ (X=Cd, Co, Sn and Zn) have been developed by hydrothermal reduction route and utilized as counter electrode (CE) in dye-sensitized solar cells (DSSCs). The purity, phase formation and morphology of the sample were characterized by X-ray diffraction, field-emission scanning electron microscopy and energy dispersive spectroscopy. The electrocatalytic activity of the synthesized selenides for the reduction of I₃^- to I^- was evaluated using cyclic voltammetry and electrochemical impedance spectroscopy. The Ni_0.9Zn_0.1Se₂ CE exhibited lower internal resistance and higher electrocatalytic activity than the other ternary metal selenides and this may be due to an increase in the electrocatalytic active sites on the surface of Ni_0.9Zn_0.1Se₂. As a result, the DSSC fabricated with Ni_0.9Sn_0.1Se₂ CE achieved a high power conversion efficiency of 4.20% under an illumination of 100 mW/cm², which is comparable to that of DSSC with Pt CE (6.11%). These results demonstrate the potential application of Ni_0.9Zn_0.1Se₂ as an alternative CE to replace expensive Pt in DSSCs. This study can be further extended for the development of new metal selenides based CE electrocatalysts with high activity for the DSSCs.

Abstract: We are presenting our results based on unsymmetrical zinc phthalocyanine by adopting ‘push-pull’ concept for the nanocrystalline dye-sensitized solar cells. Using this sensitizer in combination with nonvolatile organic-solvent-based electrolytes, we obtained a photovoltaic efficiency of 1.52% under standard global AM 1.5 sunlight and compared the results with volatile organic-solvent based electrolyte. These devices exhibit admirable stability when subjected to continuous thermal stress at 60 oC for 1000 h. The sensitizer is thermally stable up to 150 oC and can be useful for roof top applications.