Reduced optical loss in mechanically stacked multi-junction organic solar cells exhibiting complementary absorptions

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Tandem organic photovoltaic devices (OPVs) offer potential for higher efficiencies.
• Effective interconnections are crucial for optimizing performance in multi-junction OPVs.
• Optical losses due to refractive index mismatches can hinder efficiency.

Purpose of the Study:

• To develop an effective method for electrical and optical interconnections in tandem OPVs.
• To improve the power conversion efficiency of multi-junction OPVs.
• To minimize optical losses between stacked subcells.

Main Methods:

• Fabrication of a tandem OPV with a semi-transparent electrode in the first subcell.
• Utilizing complementary absorption in the second subcell.
• Employing UV-curable epoxy for mechanical stacking and air gap elimination.
• Configuring multiple contacts for series or parallel subcell connection.

Main Results:

• A tandem OPV architecture with efficient light transmission between subcells was achieved.
• UV-curable epoxy successfully eliminated air gaps, reducing optical losses.
• The multi-junction OPV demonstrated improved power conversion efficiency of approximately 6.5%.

Conclusions:

• The developed interconnection strategy is promising for effective tandem OPV fabrication.
• Mechanical stacking with UV-curable epoxy is a viable method to enhance OPV performance.
• The approach significantly reduces optical losses, leading to higher power conversion efficiencies.