A Hemispherical Image Sensor Array Fabricated with Organic Photomemory Transistors.

Area of Science:

• Organic electronics
• Semiconductor device physics
• Imaging technology

Background:

• Hemispherical image sensors offer advantages in lens design and image quality for wide-field-of-view cameras.
• Organic materials present tunable optoelectronic properties and cost-effective, low-temperature processing for sensor fabrication.

Purpose of the Study:

• To develop a photolithographic process for fabricating hemispherical image sensor arrays using organic thin film photomemory transistors.
• To demonstrate a simplified single-transistor pixel architecture for high-resolution hemispherical imaging.

Main Methods:

• Fabrication of hemispherical image sensor arrays using organic thin film photomemory transistors via photolithography.
• Characterization of the organic photomemory transistor's photoresponse, responsivity, and dark current.
• Development of a transfer method for creating damage-free hemispherical organic photomemory transistor arrays.

Main Results:

• Achieved a pixel density of 308 pixels per square centimeter.
• Demonstrated a linear photoresponse from 1 to 50 W m⁻².
• Obtained a high responsivity of 1.6 A W⁻¹ at 465 nm with a low dark current of 0.24 A m⁻² (at -1.5 V drain voltage).
• Reported the best responsivity for similar dark currents in hemispherical image sensor arrays to date.

Conclusions:

• The developed photolithographic and transfer methods enable scalable fabrication of high-resolution hemispherical organic image sensors.
• The single-transistor organic photomemory transistor design offers a promising alternative to conventional complex pixel architectures.
• These techniques are applicable to other high-resolution 3D organic semiconductor devices.