Concentration-Dependent Interfacial Engineering with a ZE-2OMe Co-adsorbent for Enhanced DSSC Performance.

Area of Science:

• Materials Science
• Electrochemistry
• Photovoltaics

Background:

• Dye-sensitized solar cells (DSSCs) efficiency relies on controlling charge transport and recombination at the TiO2/dye/electrolyte interface.
• Coadsorbents can mitigate interfacial losses and passivate surface defects, enhancing solar cell performance.

Purpose of the Study:

• To investigate the concentration-dependent effects of a novel aromatic coadsorbent, 4-[5'-(3,5-dimethoxyphenyl)-2,2'-bithien-5-yl]-benzoic acid (ZE-2OMe), on DSSC performance.
• To elucidate the mechanisms by which ZE-2OMe influences interfacial charge dynamics and overall device efficiency.

Main Methods:

• Systematic variation of ZE-2OMe concentration in DSSC fabrication.
• Characterization using optical analyses (photoluminescence, time-resolved photoluminescence), X-ray photoelectron spectroscopy (XPS), incident-photon-to-current efficiency (IPCE), electrochemical impedance spectroscopy (EIS), and J-V measurements.

Main Results:

• Low concentrations of ZE-2OMe (0.01 mM) enhanced charge collection and suppressed recombination, evidenced by increased PL intensity and longer TRPL lifetimes.
• XPS confirmed robust immobilization of ZE-2OMe on TiO2 via carboxylate anchoring.
• Enhanced short-circuit current density (Jsc) and photovoltaic conversion efficiency (PCE) from 3.5% to 5.4% at 0.01 mM ZE-2OMe, attributed to interfacial regulation, not increased light harvesting.
• Higher ZE-2OMe concentrations led to decreased device performance.

Conclusions:

• Methoxy-functionalized aromatic coadsorbent ZE-2OMe effectively improves DSSC performance by optimizing the TiO2/dye interface.
• The primary mechanism involves enhanced charge transport and suppressed recombination, with optimal performance achieved at low coadsorbent concentrations.
• ZE-2OMe represents a promising strategy for advancing DSSC technology through interfacial engineering.