The Polymer Society of Korea

Abstract

Colloidal quantum dots (CQDs) have emerged as promising materials for infrared photodetectors (IRPDs), offering high specific detectivity (D*) and compatibility with low-cost solution processing. While CQDs can support photo-induced charge multiplication, their performance in IR detection is often limited by thermal noise inherent to low-bandgap materials. Here, we report a pioneering device architecture that enables kinetically pumped avalanche multiplication in CQD-based IRPDs. By applying a strong electric field across a thick CQD layer (>540 nm), photogenerated electrons acquire sufficient kinetic energy to exceed the bandgap, thereby triggering avalanche multiplication. Tuning the dot-to-dot distance to approximately 4.1 nm optimizes the balance between impact ionization and electron hopping, enhancing charge transport and multiplication efficiency. As a result, our optimized CQD-based IRPD achieves a maximum multiplication gain of 85 and a peak detectivity of 1.4 × 10¹⁴ Jones at 940 nm. This work establishes a new platform for CQD-based photodetectors with potential for single-photon detection and ultra-high-sensitivity applications.
¹Lee at al. Nature Nanotechnology 20, 237 (2024)