[en] In this study, the characteristics of a indirect-type and flexible X-ray detector fabricated on polyethylene-naphthalate (PEN) substrate were investigated. Among the various radiation detector applications, dentistry, mammography, and non-destructive inspection areas have a significant interest in the utilization and adaption for use of a flexible and conformable imager. The fullerene-based acceptors, such as the PC₆₀BM and the PC₇₀BM, have issues with a high synthetic cost, limited spectral absorption and the incidence of a morphological instability. In order to improve the mechanical stability of the flexible detector fabricated on PEN substrate, a non-fullerene acceptor, O-IDTBR, was applied instead of PC₇₀BM acceptor. The O-IDTBR is intrinsically more ductile and the absorption wavelength of O-IDTBR was well-matched with emission wavelength of an applied CsI (Tl) scintillator. Various curvature bending tests were carried out to verify its suitability as a flexible detector. After undergoing a bending test, the detector with the P3HT:PC₇₀BM active layer showed a poor mechanical stability than the detector with the P3HT:O-IDTBR active layer.