Ultrathin Metal Mesh Transparent Electrodes for ITO-Free Organic Photovoltaics

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Metal mesh electrodes offer low cost, high transparency, and conductivity, making them attractive for electronics.
• However, large mesh spacing hinders photogenerated carrier collection, limiting their use in organic photovoltaic (OPV) devices.

Purpose of the Study:

• To develop an ultrathin metal mesh transparent electrode with optimized spacing for efficient carrier collection in OPV devices.
• To investigate the relationship between mesh geometry, transparency, and charge collection efficiency.

Main Methods:

• Fabrication of ultrathin copper/silver (Cu/Ag) mesh transparent electrodes using ultraviolet lithography.
• Fine-tuning of mesh spacing and width to optimize optical and electrical properties.
• Integration of the mesh electrode as a bottom transparent electrode in ITO-free OPV devices.

Main Results:

• An ultrathin Cu/Ag mesh electrode with 5 μm spacing and 1 μm width achieved 85% average visible transmittance (AVT) and ~200 Ω/sq sheet resistance.
• An ITO-free OPV device utilizing this mesh electrode reached a champion power conversion efficiency of 14.2%.
• A semitransparent device demonstrated 8.3% efficiency with 30.3% AVT.

Conclusions:

• Optimized ultrathin metal mesh electrodes can overcome the limitations of traditional metal meshes in OPV applications.
• This technology enables efficient ITO-free organic photovoltaic devices with tunable transparency.
• The developed Cu/Ag mesh electrodes show significant promise for next-generation transparent electronic applications.