A Study on an Organic Semiconductor-Based Indirect X-ray Detector with Cd-Free QDs for Sensitivity Improvement

Abstract

In this paper, we studied the optimized conditions for adding inorganic quantum dots (QD) to the P3HT:PC70BM organic active layer to increase the sensitivity of the indirect X-ray detector. Commonly used QDs are composed of hazardous substances with environmental problems, so indium phosphide (InP) QDs were selected as the electron acceptor in this experiment. Among the three different sizes of InP QDs (4, 8, and 12 nm in diameter), the detector with 4 nm InP QDs showed the highest sensitivity, of 2.01 mA/Gy·cm2. To further improve the sensitivity, the QDs were fixed to 4 nm in diameter and then the amount of QDs added to the organic active layer was changed from 0 to 5 mg. The highest sensitivity, of 2.26 mA/Gy·cm2, was obtained from the detector with a P3HT:PC70BM:InP QDs (1 mg) active layer. In addition, the highest mobility, of 1.69 × 10−5 cm2/V·s, was obtained from the same detector. Compared to the detector with the pristine P3HT:PC70BM active layer, the detector with a P3HT:PC70BM:InP QDs (1 mg) active layer had sensitivity that was 61.87% higher. The cut-off frequency of the P3HT:PC70BM detector was 21.54 kHz, and that of the P3HT:PC70BM:InP QDs (1 mg) detector was 26.33 kHz, which was improved by 22.24%.

High-Efficiency ZnS: Cu+, Al3+ Scintillator for X-ray Detection in a Non-Darkroom Environment

“…X-ray detecting has been widely utilized in industrial material inspection, lesion diagnosis, and scientific research. − Theoretically, X-ray detectors can be divided into direct and indirect types, in which the latter is cheaper and more stable. − However, common detection methods require sophisticated equipment and stringent environmental conditions, the scintillator signal will be treated further before it is fed back to the operator, especially the indirect detection, which collects the visible light signal from scintillator conversion in a non-darkroom. Due to the light adaptation phenomenon of human eyes, it is facile for people to observe luminescent objects in the dark .…”

A Study on Improving the Sensitivity of Indirect X-ray Detectors by Adding Hybrid Perovskite Quantum Dots

“…In addition, bulk-type perovskite materials have the advantages of long carrier diffusion length, low defect density and high carrier mobility, so they are applied to solar cells [30,31], detectors [32,33] and phototransistors [34]. Among these, the X-ray detector is being used as the core of non-destructive testing, and the higher the sensitivity per area, the easier it is to apply, so research in the field is expanding [35][36][37][38][39]. Xray detectors are divided into two types: direct detection and indirect detection, depending on whether or not a detector is coupled to the scintillator.…”

Ultrasonically Processed WSe2 Nanosheets Blended Bulk Heterojunction Active Layer for High-Performance Polymer Solar Cells and X-ray Detectors

“…A wide-bandgap polymer, 5,7-Bis(2-ethylhexyl)benzo[1,2-c:4,5-c ]dithiophene-4,8-dione (PBDB-T) is one of the most recognized and effective donor materials in polymer solar cells (PSC). Moreover, most organic-based semiconducting devices use a fullerene derivative phenyl-C70-butyric acid methyl ester (PCBM) as an acceptor due to its high rate of conductivity, which is combined with the photon charge conversion layer (active layer) [17][18][19][20][21]. Among the donor materials, PBDB-T-conjugated polymers are the most studied and well-recognized choice of material due to their unique properties, such as semicrystalline structure and high hole/electron mobility, as well as their ease of interaction with fullerene-based acceptors such as PCBM [22].…”

“…The coupling of an indirect photodetector and a CsI (T1) scintillator is a common detection method in which the scintillator converts incidental X-rays into visible light. The visible light is then absorbed by the active layer, thereby forming an electron-hole pair to excite charge carriers [21,40]. In a recent report, an X-ray detector based on a ternary system was studied.…”