Performance Enhancement by Secondary Doping in PEDOT:PSS/Planar-Si Hybrid Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Solar cell efficiency relies on light absorption and charge conversion.
• Optimizing conductivity and minimizing optical losses are crucial for higher photoconversion efficiency.
• Hybrid solar cells utilize organic conductive polymers like PEDOT:PSS on inorganic substrates.

Purpose of the Study:

• To investigate the impact of post-treatment on PEDOT:PSS films in hybrid solar cells.
• To compare the effects of cosolvent addition versus post-treatment on film properties and cell performance.
• To determine optimal methods for enhancing conductivity and photoconversion efficiency.

Main Methods:

• Fabrication of hybrid solar cells using PEDOT:PSS on n-type silicon.
• Application of three PEDOT:PSS film conditions: pristine, cosolvent-enhanced (ethylene glycol), and post-treated (ethylene glycol/methanol mixture).
• Characterization of film conductivity, absorbance, and overall cell photoconversion efficiency across 72 samples.

Main Results:

• Post-treatment yielded the highest conductivity (1334 S/cm) compared to cosolvent-enhanced (637 S/cm) and pristine films (0.8 S/cm).
• Post-treated cells demonstrated the highest photoconversion efficiencies, improved open-circuit voltage, and fill factor.
• Cosolvent-enhanced films showed higher short-circuit current density but lower overall efficiency than post-treated films, attributed to increased PEDOT:PSS absorbance.

Conclusions:

• Post-treatment with an ethylene glycol/methanol mixture is a reproducible method for significantly enhancing PEDOT:PSS conductivity and hybrid solar cell efficiency.
• Achieving high conductivity and efficiency requires balancing electrical improvements with optical properties like absorbance.
• This study highlights the trade-offs in optimizing hybrid solar cell performance through material post-processing.