Bonding of Shortwave Infrared Organic Photodetectors on Silicon via Conducting Polymer Glue for Image Sensor Applications

Abstract

Integrating organic photodetectors (OPDs) with silicon (Si)-based readout integrated circuits presents numerous challenges, particularly due to the degradation of organic semiconductors (OSCs) caused by various stresses. This issue is especially pronounced in narrow bandgap OSCs with shortwave infrared (SWIR) spectral responses, further complicating the development of organic image sensors. To address the issue, we draw inspiration from silicon- and germanium-based sensor technology, proposing a method of first fabricating bottom-illuminated SWIR OPD devices on a glass substrate and then bonding the OPD onto a Si substrate using a poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) glue to form a top-illuminated device. This architecture avoids exposing the OPDs to high temperatures and plasma bombardment during the thin-film deposition, and the glass substrate can also serve as an ideal encapsulation cover, offering a new direction for the integration of OPD-on-Si technology. Eventually, the bonded, top-illuminated device achieves a detectivity of 3.58 × 10¹⁰ Jones at 1290 nm and −2 V bias. This advancement not only enhances the integration completeness of OPDs with Si semiconductors but also preserves the intrinsic performance of OSC materials, further bringing revolutionary changes to the organic sensing industry.