High-Performance Solution-Processed Quantum Dot Infrared Photodetectors via Interface Engineering with MXenes

Infrared (IR) photodetectors are crucial for a range of applications, including night vision, optical communication, and environmental monitoring. However, their effectiveness is often hindered by low charge transport and interfacial losses in colloidal quantum dot (CQD)-based designs. MXenes, known for their high metallic conductivity, adjustable surface terminations, and excellent optical transparency, present a unique opportunity to improve interfaces for better optoelectronic performance. In this work, Ti₃C₂T_<i>x</i> MXene via interface engineering for PbS CQD IR photodetectors, in which it functions as an electrode, transport layer, and interfacial modifier is systematically investigated. As a result, an ultrahigh responsivity of 1032.37 A/W with a specific detectivity of 1.12 × 10¹³ Jones and an external quantum efficiency of 1.311 × 10⁵ % are obtained from photodetector ITO/ZnO/Ti₃C₂T_<i>x</i>/PbS/MoO₃/Ti₃C₂T_<i>x</i> under 1 μW/cm² 980 nm illumination. Our finite difference time domain (FDTD) simulations further support and provide a physical basis for our experimental results, indicating that dual MXene incorporation significantly enhances optical field confinement and absorption within the PbS CQD layer. Thus, it illustrates that MXene-enabled interface engineering and optical coupling can establish an effective design paradigm for high-performance, solution-processed infrared photodetectors, effectively bridging the gap between quantum materials and practical optoelectronics.