Molecular Weight Tuning of Organic Semiconductors for Curved Organic–Inorganic Hybrid X‐Ray Detectors

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.

High‐Quality 0D Cs4PbBr6‐Based Dense Wafer for High‐Sensitivity X‐Ray Detection and High‐Resolution Imaging in Harsh Environment

“…The optimal XDs exhibited an industrial-level dark current of 61 pA (6.7 pA mm −2 ) and a photocurrent of 247 nA (Figure 3b) under a bias electrical field of 6667 V cm −1 . [29] Such an impressive improvement could be attributed to the efficient trade-off between charge extraction and X-ray absorption, inhibited recombination loss and restraint ion migrations (detailly discussed in Figure S10, Supporting Information). [44] To quantitatively evaluate the response capacity, the resistivity was calculated and the results are depicted in Figure 3c.…”

“…For example: a) the reproducibility and homogeneity of the manufacturing process need to be improved to satisfy the demands of industrial production; b) the manufacturing parameters optimization needs to be studied carefully according to the properties of the materials to realize high sensitivity, low dark current (<10 pA mm −2 ), and low detection limit simultaneously. [29,30] In this work, we demonstrated high dense and high-quality 0D Cs 4 PbBr 6 wafers for high-performance X-ray detections in harsh environment for the first time, which were fabricated by an optimized size-scalable hot isostatic-pressed strategy. Density functional theory (DFT) and experiment measurement reveal that defect concentrations were restrained by slowing the crystallization speed, eventually bringing down the dark current and improving the X-ray response.…”

“…For example: a) the reproducibility and homogeneity of the manufacturing process need to be improved to satisfy the demands of industrial production; b) the manufacturing parameters optimization needs to be studied carefully according to the properties of the materials to realize high sensitivity, low dark current (<10 pA mm −2 ), and low detection limit simultaneously. [ 29,30 ]…”

Spontaneously Induced Hierarchical Structure by Surface Energy in Novel Conjugated Polymer‐Based Ultrafast‐Response Organic Photodetectors

“…MoO x (≈8 nm) and Ag (≈100 nm) layers were deposited by thermal evaporation under a vacuum of ≈10 −6 Torr for the hole-transporting layer (HTL) and electrode, respectively. The calculated active layer was 0.0707 cm 2 .…”

“…OPDs are currently being studied for use in X-ray photodetectors, optical fingerprint sensors, and high-resolution visible/near infrared image sensors. [2] A photoconductive layer that can increase the photocurrent density (J ph ) and decrease the dark current density (J d ) in OPDs is fundamental to photodetection. [3] A larger difference between J ph and J d improves the on/off ratio of the OPDs, and the key OPD parameters related to the J ph and on/off ratio are the responsivity (R) and specific detectivity (D*), respectively.…”