Flexible Organic X‐Ray Sensors: Solving the Key Constraints of PET Substrates

Abstract

Organic semiconductor‐based sensors are a unique class of wearable x‐ray detectors, as the response from their carbon‐based composition can mimic the response of the human body to radiation. A thin (260 nm) flexible P3HT: o‐IDTBR‐based organic sensor, deposited onto a conductive Kapton substrate is demonstrated, can provide precise and artifact‐free dosimetry under synchrotron x‐rays with sensitivities of (1958 ± 31)pCGy−1cm−2 without bias. The sensor is capable of accurately resolving multiple 50 µm‐wide x‐rays with a full‐width‐half‐max of (51.6 ± 1.9)µm for a range of energies (47–87.5)keV and dose‐rates (0.21–0.45)kGy s−1. Organic sensors fabricated with plastic polyethylene substrates exhibit unreliable x‐ray responses and broadening of the full‐width‐half‐max. Simulations reveal that x‐ray induced electrostatic charge generated from the polyethylene causes a reverse polarity of the signal. X‐ray charge mapping shows the effective area sensitized with the polyethylene device extends twice the length of the pixel area, while sensors with Kapton substrates closely match the expected active area. Radiation tolerance of P3HT:o‐IDTBR devices maintain 85.4% of the initial x‐ray sensitivity after 10 kGy with similar radiation tolerances to amorphous silicon. This study confirms the unsuitability of polyethylene substrates for flexible radiation detectors, providing the first evidence of the quantitative and spatial resolution limitations created by the generation of radiation‐induced charge.