Organic Solvent-Based PEDOT:PSS Solution for Air-Processed Organic Photovoltaics

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is a key hole transport material (HTM) in organic photovoltaics (OPVs).
• Aqueous PEDOT:PSS (a-PEDOT) exhibits poor wettability, limiting its use as a hole transport layer (HTL) in inverted OPVs.
• Improved HTL materials are crucial for advancing solution-processed inverted and tandem OPV architectures.

Purpose of the Study:

• To develop an organic solvent-based PEDOT:PSS (o-PEDOT) with enhanced wettability for inverted OPVs.
• To investigate the potential of o-PEDOT as an interconnection layer (ICL) in air-processed tandem OPVs.
• To demonstrate high-efficiency solution-processed and flexible tandem OPV devices using o-PEDOT.

Main Methods:

• Preparation of o-PEDOT using a solvent-replacement method involving centrifugal ultrafiltration, dialysis membrane, and thermal evaporation.
• Fabrication of inverted OPVs utilizing o-PEDOT as the HTL on the active layer.
• Integration of o-PEDOT as an ICL in air-processed tandem OPV devices.

Main Results:

• Successfully fabricated inverted OPVs using solution-processed o-PEDOT as the HTL.
• Achieved a champion power conversion efficiency (PCE) of 15% for air-processed tandem OPVs with o-PEDOT as the ICL.
• Demonstrated flexible tandem OPVs with o-PEDOT as the ICL, achieving over 14% efficiency.

Conclusions:

• o-PEDOT offers improved wettability, enabling its use as an HTL in solution-processed inverted OPVs.
• The good conductivity and suitable work function of o-PEDOT make it an effective ICL for tandem OPVs.
• This work presents a viable pathway for high-performance, solution-processed, and flexible tandem OPVs.