Bifunctional Etalon-Electrode To Realize High-Performance Color Filter Free Image Sensor

Area of Science:

• Optoelectronics
• Organic electronics
• Semiconductor devices

Background:

• Organic photodiodes (OPDs) offer advantages for image sensors, including thin profiles and potential for high integration.
• Current OPDs lack inherent color selectivity and struggle to maintain high detectivity at thin (<1 μm) thicknesses.
• Existing image sensor designs often rely on bulky color filters, limiting integration.

Purpose of the Study:

• To develop OPDs with intrinsic color selectivity and high detectivity in a thin form factor.
• To introduce a novel
• etalon-electrode
• concept for integrated color filtering in OPDs.
• To demonstrate a prototype image sensor utilizing the new OPD architecture.

Main Methods:

• Designed a novel OPD architecture incorporating an etalon-electrode, a panchromatic organic active layer, and a counter electrode.
• Precisely adjusted the etalon-electrode's thickness composition to achieve narrowband R-/G-/B-selective detectivity spectra.
• Fabricated and characterized R-/G-/B-selective OPDs with thicknesses under 800 nm.

Main Results:

• Achieved well-defined narrowband R-/G-/B-selective detectivity spectra using the etalon-electrode.
• Maintained OPD thickness below 800 nm for all color-selective devices.
• Demonstrated high average detectivity values exceeding 10¹² cm·Hz^0.5/W.
• Successfully fabricated a 10 × 10 image sensor prototype with 500 μm pixel pitch.

Conclusions:

• The etalon-electrode concept effectively imparts color selectivity to OPDs while preserving thinness and high detectivity.
• This technology facilitates facile full-color patterning for advanced image sensor integration.
• The developed OPDs are promising for next-generation, highly integrated color image sensors.