High-performance photomultiplication-type quantum dot IR photodetectors at low applied voltages

Narrow bandgap colloidal quantum dots (CQDs) are ideal materials for realizing high-sensitivity infrared photodetectors. Their use is an effective way to improve the external quantum efficiency (EQE) by utilizing the photomultiplication (PM) effect to achieve highly sensitive photodetection. How to improve the device performance by photomultiplication is still the hot topic in this field. In this work, a simple method of inserting a gold nanoparticles (Au-NPs) film into the PbS QDs active layer to enhance light absorption for the PM-type photodetector ITO/ZnO/PbS/Au-NPs/PbS/P3HT/Ag is presented. In this case, Au-NPs act as the hole traps to induce the tunneling injection of external electrons. As a result, a high responsivity of 1088.86 A W−1 with a high EQE of 138 066% and a specific detectivity (D*) of 1.2 × 1014 Jones is observed from the PM-type photodetector ITO/ZnO(80 nm)/PbS(110 nm)/Au-NPs(4 nm)/PbS(110 nm)/P3HT(140 nm)/Ag under 0.2 μW cm−2 980 nm illumination at −1 V. Furthermore, the device configuration of the photodetector is optimized with the help of COMSOL simulation, and its maximum absorption reaches 91%. In addition, the feasibility of enhancing light absorption through the plasmonic effect has been confirmed by simulating the electric field distribution and carrier distribution within the photodetector.