Enhanced power conversion efficiency of organic solar cells by embedding Ag nanoparticles in exciton blocking layer

• Ag nanoparticles were prepared and embedded into the exciton blocking layer.
• The power conversion efficiency was enhanced with the Ag nanoparticles.
• The cell series resistances decreased with the Ag nanoparticles.
• The optical absorptions in the cell increased with the Ag nanoparticles.
• The performance enhancements relied on the location of Ag NPs.

We demonstrate the power conversion efficiency of bulk heterojunction organic solar cells can be enhanced by introducing Ag nanoparticles into organic exciton blocking layer. The Ag nanoparticles were incorporated into the exciton blocking layer by thermal evaporation. Compared with the conventional cathode contact materials such as Al, LiF/Al, devices with Ag nanoparticles incorporated in the exciton blocking layer showed lower series resistances and higher fill factors, leading to a 3.2% power conversion efficiency with a 60 nm active layer; whereas, the conventional devices have only 2.0–2.3% power conversion efficiency. Localized surface plasmon resonances by the Ag nanoparticles and their contribution to photocurrent were also discussed by simulating optical absorptions using a FDTD (finite-difference-time-domain) method.

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