A study on sensitivity improvement of indirect-type X-ray detectors using a ternary-blend organic active layer

The aims of this study is to improve the sensitivity of indirect X-ray detectors by investigating the properties and application of ternary-blended organic active layers. The ternary-blended active layers studied were composed of conjugated polymer PBDB-T-2F as the donor (D1), non-fullerene Y6 as the first acceptor (A1) and ITIC-4F as the second acceptor (A2). The structural similarity between the two acceptors allows the advantage formation of a homogeneous acceptor phase and results in good film morphology. Another advantage of our approach is the electrical and optical characteristics of the active layer can be modulated based on the mixing ratio of the two acceptors. To find the optimal ternary blending, the content of D1 was fixed while the A1:A2 content ratio was adjusted. The CsI (Tl) scintillator-coupled detector with an active layer of PBDB-T-2F:Y6:ITIC-4F = 1.0:0.6:0.4 achieved the highest sensitivity of 4.27 × 10 3 μC∙Gy air −1 ∙cm −2 giving respective improvements of 27.10% and 43.92% compared to binary-blend PBDB-T-2F:Y6 = 1:1 and PBDB-T-2F:ITIC-4F = 1:1. Next, the active layer's spin-coating conditions and the bias conditions were examined to further improve the sensitivity of the detector. Finally, the detector with a PBDB-T-2F:Y6:ITIC-4F = 1.0:0.6:0.4 active layer was shown to have the highest sensitivity of 5.42 × 10 3 μC∙Gy air −1 cm −2 at a bias of – 1.6 V with a 97 ± 2 nm thick active layer. The aims of this study are to improve the sensitivity of indirect X-ray detectors by investigating the properties of ternary-blended organic active layers. The structural similarity between the two acceptors allows the advantage formation of a homogeneous acceptor phase and results in good film morphology. Another advantage of our approach is the electrical and optical characteristics of the active layer can be modulated based on the mixing ratio of the two acceptors. The CsI (Tl) scintillator-coupled detector with ternary-blended active layer giving respective improvements of 27.10% and 43.92% compared to binary-blended active layer. • To improve the sensitivity of the X-ray detector, a ternary-blend strategy was applied to the organic active layer. • The X-ray detector using ternary-blended active layer shown 27.10% and 43.92% higher sensitivity compared to their respective binary combinations (PBDB-T-2F:Y6 and PBDB-T-2F:ITIC-4F). • The indirect-type X-ray detector using PBDB-T-2F:Y6:ITIC-4F = 1.0:0.6:0.4 ternary-blended active layer was achieved a high sensitivity of 5.42 × 10 3 μC∙Gy air −1 ∙cm −2 .