Understanding and Countering Illumination-Sensitive Dark Current: Toward Organic Photodetectors with Reliable High...

Area of Science:

• Materials Science
• Organic Electronics
• Photodetector Technology

Background:

• Organic photodetectors (OPDs) show promise for broadband sensing due to enhanced photoresponsivity and suppressed dark current.
• However, reliable photosensing in high-performance inverted OPDs is challenged by dark current sensitivity to illumination history.

Purpose of the Study:

• To investigate the universal phenomenon of detrimental dark current sensitivity to illumination history in high-performance inverted OPDs.
• To address the underlying cause of this sensitivity, which impacts device performance and consistency.

Main Methods:

• Systematic studies were conducted to understand the effect of high-energy photons on commonly used electron transport layers in OPDs.
• A novel "double" layer tin oxide was introduced as an alternative electron transport layer.

Main Results:

• The study identified the loss of charge selectivity in conventional electron transport layers as the cause of dark current instability.
• The "double" layer tin oxide electron transport layer successfully eliminated the inconsistency between initial and post-illumination dark current.
• The new electron transport layer maintained low dark current, good external quantum efficiency, and rapid transient response.

Conclusions:

• The sensitivity of dark current to illumination history is a critical issue in high-performance inverted OPDs.
• The developed "double" layer tin oxide electron transport layer offers a robust solution, enabling stable and reliable organic photodetector performance.