Siloxane Molecular Glue for Ultrarobust Interface Engineering in High-Performance Colloidal Quantum Dot Infrared Image Sensors.

Abstract

Interfacial defects and poor mechanical robustness critically limit the performance of colloidal quantum dot (CQD) photodiodes for infrared imaging. Here, we introduce a bifunctional organosilane, (3-mercaptopropyl) methyldimethoxysilane (MDMS), as an interfacial layer to simultaneously address these challenges in inverted PbS CQD photodiodes. MDMS molecules form robust covalent bridging at the CQDs/electron transport layer (ETL) interface through thiol-based coordination and hydrolysis-condensation into a cross-linked siloxane network. This interface engineering not only reinforces mechanical adhesion (achieving 5B rating in ASTM D3359 tests vs. 0B/1B for C₆₀ controls) but also provides an ideal nucleation surface for ALD-grown SnO₂ ETL, suppressing island-like growth and interfacial defects. The optimized devices deliver a specific detectivity of 2.37×10¹² Jones at 1550 nm under 0 V while maintaining 79% EQE under -0.1 V, with dark current reduced by >50% compared to C₆₀-based controls. Monolithic integration with a silicon ROIC yields a SWIR imager with outstanding photoresponse non-uniformity (2.8%) and spatial resolution (26 lp/mm at 50% MTF), demonstrating silicon wafer perspectivity and material discrimination. This work provides an efficient strategy for addressing interfacial issues in CQD optoelectronics.