Abstract
Curved X‐ray detectors have the potential to revolutionize diverse sectors due to benefits such as reduced image distortion and vignetting compared to their planar counterparts. While the use of inorganic semiconductors for curved detectors are restricted by their brittle nature, organic–inorganic hybrid semiconductors which incorporated bismuth oxide nanoparticles in an organic bulk heterojunction consisting of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) and [6,6]‐phenyl C71 butyric acid methyl ester (PC70BM) are considered to be more promising in this regard. However, the influence of the P3HT molecular weight on the mechanical stability of curved, thick X‐ray detectors remains less well understood. Herein, high P3HT molecular weights (>40 kDa) are identified to allow increased intermolecular bonding and chain entanglements, resulting in X‐ray detectors that can be curved to a radius as low as 1.3 mm with low deviation in X‐ray response under 100 repeated bending cycles while maintaining an industry‐standard dark current of <1 pA mm−2 and a sensitivity of ≈ 0.17 μC Gy−1 cm−2. This study identifies a crucial missing link in the development of curved detectors, namely the importance of the molecular weight of the polymer semiconductors used.
Highlights
Minimization of image distortion toward the edge of the viewing field and reduced vignetting.[] In this regard, the human eye with its curved design is still regarded as the ideal example of a curved image detec
Four different molecular weights of P3HT (25, 37, 46, and 55 kDa labelled as P3HT A, B, C, and D, respectively) were selected for this study to cover a wide range of MW typically used for P3HT based optoelectronic devices (Figure 1b)
All the NP-bulk heterojunction (BHJ) films were processed in a similar manner and maintained at a constant thickness of ≈ 55 μm
Summary
In order to understand the impact of P3HT MW on detector performance, rigid NP-BHJ X-ray detectors (Figure 1a) were fabricated based on the hole transport layer free architecture as previously reported by us.[14].  where Pmax is the maximum value of applied load (10 mN) and  is the real projected contact area of the indenter which is given as 24.56hc2.[55] A similar trend was observed for hardness where films fabricated with P3HT A, B, C, and D displayed hardness values of 138, 105, 110, and 111 MPa, respectively Both the reduction in stiffness as well as hardness with increasing MW is in agreement with the trend of lower crystallinity observed for higher MW and to the possibility of interchain P3HT entanglements as discussed previously based on the Scherrer analysis of the GIWAXS measurements. The detectors did not display a significant degradation upon repeated bending, with a maximum deviation of around 2.7%, 2.4%, and 2.8% for charge density (or sensitivity) being observed for P3HT D/75 μm, P3HT C/75 μm, and P3HT D/50 μm detectors, respectively
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
