A High-Sensitivity Flexible Direct X-ray Detector Based on Bi2O3/PDMS Nanocomposite Thin Film

Sensitivity improvement of hybrid active layer containing 2D nanoplatelets for indirect x-ray detector

In this paper, we attempted to improve the detection sensitivity of an indirect x-ray detector through using a hybrid active layer composed of a poly [N-90-heptadecanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT) organic semiconductor and cadmium selenide nanoplatelets (CdSe NPLs) colloidal inorganic semiconductors. First, different blending ratio in the active layer (i.e. 2:1, 1:1, 1:2 and 1:3) of PCDTBT:CdSe NPL were examined, a sensitivity of 89.5μC·Gy_air^-1·cm^-2was achieved using a 1:1 ratio due to the low series resistance (R_S) and defect density in this configuration. Then, the oleic acid (OA) that was initially applied in the CdSe NPL surface was replaced with pyridine ligands, this was done because the pyridine ligand is a short-chain ligand that can help charge transfer by reducing the distance between NPLs in the active layer. In addition, an experiment was conducted to determine the optimal ligand exchange time. A detector with an PCDTBT:CdSe NPL active layer fabricated using pyridine ligand exchange achieved a sensitivity of 219.8μC·Gy_air^-1·cm^-2after an exchange time of 12 h, this is an improvement of 155% compared to the detector using a PCDTBT:CdSe NPL with the original OA ligands. Lastly, the optimal thickness for the PCDTBT:CdSe NPL active layer was investigated. The highest mobility of 7.60 × 10^{- 6}cm²/V·s was recorded after fabricating the layer using spin-coating at 1900 rpm, the highest sensitivity of 314.0μC·Gy_air^-1·cm^-2was also achieved under these conditions. Compared to the initial state of the detector, our modifications improved the sensitivity of the PCDTBT:CdSe NPL detector by 251%.

Characteristics of the Colorless Polyimide-Based Flexible X-ray Detector with Non-Fullerene Acceptor Polymer

In this paper, we investigate the characteristics of the colorless polyimide (CPI) film-based flexible organic X-ray detector. The CPI film can be applied to various applications, because it shows excellent visible light transmittance by removing the yellow color of polyimide (PI) film, which has the advantage of physical and chemical stability. In addition, the deformation curvature of the CPI substrate according to temperature showed similar characteristics to that of the glass substrate. For the organic active layer of the proposed detector, PBDB-T was fixed as a donor, and PC₇₁BM and ITIC were used as acceptors. To evaluate the mechanical stability of the flexible detector, the degradation sensitivity was measured as bending curvature and bending cycle. The sensitivity of the detector with ITIC acceptor showed a 46.82% higher result than PC₇₁BM acceptor on bending curvature (R = 10); and at the same curvature, when the bending cycle was 500 times, a 135.85% higher result than PC₇₁BM acceptor.