Electrohydrodynamic Jet-Printed X-ray Sensor Based on Iodide-Exchanged Lead(II) Sulfide Quantum Dots

Abstract

The detection of X-rays through innovative solution-processable semiconductors is gaining increasing attention for their widespread applicability in several fields, such as radiology, radiation therapy, and security. Reliable and controllable deposition techniques are pivotal to ensure the repeatability and optimization of devices based on such materials. Here, we used electrohydrodynamic jet (EHD-Jet) printing to fabricate X-ray detectors based on lead sulfide (PbS) quantum dots (QDs) treated with tetrabutylammonium iodide (TBAI). EHD-Jet printing offers significant advantages for scalable device production, allowing precise control over the deposition of the active layer, from nanometer to micrometer thicknesses, which is crucial for tuning device performance. Using a parallel setup with a reference boron-doped diamond dosimeter, we demonstrate a response of the active layer constituted of iodine-exchanged PbS QDs (I-PbS) to hard X-rays (22 keV) with a low-voltage biasing of 1 V. The devices show a linear current–dose rate relation. The best surface-specific sensitivity and limit of detection of S = 431 ± 30 μCGy_air^–1 cm^–2 and LoD = 506.71 nGy_airs^–1, respectively, are measured, with 10–90% rise/fall times that were found to be <500 ms. This sensitivity is one order of magnitude higher than reported values for commercially available amorphous selenium.