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%.
Highlights
Colloidal semiconductor nanocrystals (NCs), such as quantum dots (QDs), nanowires (NWs), and nanoplatelets (NPLs), are being widely studied [1,2,3,4]
The absorbance of the P3HT:PC70BM blended with different sizes of indium phosphide (InP) QDs was higher than the absorbance of the pristine P3HT:PC70BM film, because QDs have a high extinction was higher than absorbance of the pristine film, because QDs a highbyextinction coefficient
We studied the method of adding inorganic QDs to the organic active layer in order to improve the detection sensitivity of the indirect X-ray detector
Summary
Colloidal semiconductor nanocrystals (NCs), such as quantum dots (QDs), nanowires (NWs), and nanoplatelets (NPLs), are being widely studied [1,2,3,4]. In the field of radiation detectors, there is a growing trend of research on mixing them with organic semiconductors and NCs, such as hybrid or additives architecture, to improve detection sensitivity [13,14]. The indirect detection is combined with a scintillator, which absorbs X-ray photons, converts them into visible photons, and generates electron–hole pairs because of the incident visible photons in the active layer of the photodetector. The generated emission transfers photon energy to the active layer and creates additional charge carriers, which improve the performance of the detector. The X-ray detector performances could be evaluated in advance by means of the Jsc. After the photodetector evaluation, it was combined with a scintillator to evaluate the detector characteristics, such as collected current density (CCD), dark current density (DCD), and detection sensitivity under X-radiation.
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