Influence of Different Cations of N3 Dyes on Their Photovoltaic Performance and Stability

The N3 dye was modified by substituting two of its protons by potassium or sodium cations. The performance and stability of dye-sensitized solar cells incorporating the new dyes were evaluated under light soaking<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo><mml:mn>1000</mml:mn><mml:mtext> </mml:mtext><mml:mtext>W</mml:mtext><mml:mo>⋅</mml:mo><mml:msup><mml:mrow><mml:mtext>m</mml:mtext></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mo>)</mml:mo></mml:mrow></mml:math>at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mn>50</mml:mn><mml:mo>∘</mml:mo></mml:msup><mml:mtext>C</mml:mtext></mml:math>. Photocurrent measurements demonstrated that proton substitution by potassium cations rends the system more stable. Further characterization of the potassium-based devices was performed by electrochemical impedance spectroscopy to investigate the charge-transfer phenomena occurring at the different interfaces of the cells.