Innovative materials for direct X-ray detection: organic semiconductors and 2D transition metal dichalcogenides

The objective of this experimental work was to evaluate the performance of thin-film X-ray detectors represented as thin-film transistors and based on transition metal dichalcogenide MoS2 and on a fully organic semiconductor 1,4,8,11-tetramethyl-6,13-triethylsilylethynyl pentacene (TMTES) blended with polystyrene (PS) with the TMTES:PS ratio of 17:3, 9:1, 19:1 and 39:9. As a result, the average sensitivity of the MoS2-based photodetectors was estimated to lie in the range between 10^11 and 10^12 µC/(Gy·cm^3), while the TMTES:PS exhibited the sensitivity per unit area of (3.4 ± 1.3) × 10^3 µC/(Gy·cm^2) and (2.7 ± 0.8) × 10^3 µC/(Gy·cm^2) for the TMTES:PS ratio of 17:3 and 9:1, respectively. Such sensitivity per unit area is one order of magnitude lower than that evaluated for the MoS2-based devices. Additionally, in combination with previous research conducted on the TMTES:PS X-ray detectors, it was found that the overall performance of the devices deteriorates with the reduction of relative amount of PS in the blend. On the whole, both types of photodetectors perform excellent characteristics upon X-ray exposure, which provides motivation for further research on the MoS2 and TMTES:PS semiconductor applications in direct X-ray detection.