Flexible Solution-Processed Electron-Transport-Layer-Free Organic Photovoltaics for Indoor Application

Area of Science:

• Materials Science
• Energy Science
• Device Physics

Background:

• Organic photovoltaics (OPVs) offer advantages like flexibility and solution processability for Internet of Things (IoT) devices.
• Challenges remain in achieving operational stability and scalable fabrication for flexible OPVs.
• Current encapsulation methods are insufficient to address degradation from internal and external factors in thick active layers.

Purpose of the Study:

• To develop flexible, solution-processed organic photovoltaics (OPVs) with improved indoor efficiency and long-term operational stability.
• To overcome limitations of thin active layers vulnerable to defects and low yield rates.
• To propose a simplified fabrication process for large-scale OPV manufacturing.

Main Methods:

• Fabrication of flexible OPVs using a thick active layer and solution-processed electrodes.
• Utilizing a spontaneously formed gallium oxide layer on a eutectic gallium-indium surface as a barrier.
• Employing spin-coated silver nanowires as bottom electrodes without complex flattening.

Main Results:

• Achieved improved indoor efficiency and long-term operational stability compared to conventional OPVs.
• Prevented fast degradation by leveraging the oxygen and water vapor barrier of gallium oxide layers.
• Maintained 93% of initial maximum power (Pmax) after 5000 minutes of indoor operation under LED illumination.
• Enabled direct use of silver nanowire electrodes, simplifying fabrication.

Conclusions:

• Flexible, solution-processed OPVs with enhanced stability and simplified fabrication are demonstrated.
• The gallium oxide barrier effectively mitigates degradation, crucial for IoT applications.
• The study presents a promising manufacturing technique for high-throughput energy demands in flexible electronics.