Sulfur-doped molybdenum oxide anode interface layer for organic solar cell application

Area of Science:

• Materials Science
• Renewable Energy
• Organic Electronics

Background:

• Organic solar cells (OSCs) offer a promising avenue for renewable energy generation.
• Efficient anode interface layers (AILs) are crucial for optimizing charge extraction and device performance in OSCs.
• Molybdenum oxide (MoO3) is a common AIL, but its efficiency can be limited.

Purpose of the Study:

• To investigate the effect of sulfur doping on molybdenum oxide (MoO3) as an anode interface layer in organic solar cells.
• To understand how sulfur doping modulates the electronic properties of MoO3.
• To enhance the photovoltaic performance of OSCs by optimizing the AIL.

Main Methods:

• Fabrication of OSCs using regioregular poly(3-hexylthiophene):fullerene derivative composites.
• Sputtering of sulfur-doped molybdenum oxide (S-MoO3) films as AILs on indium tin oxide (ITO) substrates.
• Characterization using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) to analyze electronic properties.

Main Results:

• Oxygen flow ratio controlled sulfur doping, tuning Mo(+4)/Mo(+5)/Mo(+6) ratios, Fermi level, electron affinity, ionization energy, and band gap of MoO3.
• Sulfur doping created partially occupied Mo 4d-bands, shifting the valence band closer to the Fermi level and rendering S-MoO3 a p-type semiconductor.
• OSCs with S-MoO3 AILs achieved a power conversion efficiency of 3.69%, a 12% improvement over pure MoO3 AILs.

Conclusions:

• Sulfur doping is an effective strategy to modify the electronic structure and improve the hole-transport properties of MoO3.
• Optimized S-MoO3 AILs significantly enhance the performance of organic solar cells.
• This research provides a pathway for developing more efficient anode interface materials for organic electronics.