Solution-Processed Organic Photodetector Using Hafnium Oxide as an Electron Blocking Layer.

Area of Science:

• Organic electronics
• Photodetector technology
• Materials science

Background:

• Leakage current significantly impacts organic photodetector (OPD) performance.
• Electron blocking layers are crucial for minimizing leakage current in OPDs.

Purpose of the Study:

• To decrease leakage current in organic photodetectors.
• To introduce hafnium oxide (HfO₂) as an effective electron blocking material.

Main Methods:

• Fabrication of an OPD with the structure ITO/HfO₂/PCHT:PC₆₀BM/Yb/Al using a solution process.
• Measurement of J-V characteristics, external quantum efficiency, and transient photocurrents.
• Systematic variation of hafnium oxide layer thickness.

Main Results:

• The thickness of the HfO₂ layer critically influenced the OPD's detectivity.
• An OPD with a 5.5 nm HfO₂ film achieved an on-off current ratio of 2.26 × 10⁵ at -1 V.
• This performance is double that of devices using a PEDOT:PSS electron blocking layer.

Conclusions:

• Ultrathin hafnium oxide is a highly effective electron blocking material for organic photodetectors.
• Solution-processed hafnium oxide offers a promising route to enhance OPD performance.
• The study demonstrates a significant improvement in OPD on-off current ratio using HfO₂.