Fig. 1: Flexible fully organic indirect proton detector.

a Detector cross-section scheme. The layer dimensions and relative thicknesses are out of scale. Chemical structures and thicknesses of the organic semiconductor and the scintillator layers are also indicated. b Flexible indirect proton detector 2 × 2 matrices. c, d Monte Carlo simulations of a single treatment run, reaching a total dose of 2 Gy on the cancer volume by protons irradiation with energy in the range (162 ÷ 197) MeV: dose distribution as % of 78 GyRBE (c) and dose-average LET distribution as % of 4 keV µm⁻¹ (d). e Simulated curves of the energy loss of each 5 MeV proton impinging in PSS100-(red) and PVP-MPS-(green) based scintillators. The area below the curves corresponds to the total energy released inside the material. f Reliability of the detector response benchmarked by measuring the photocurrent signal rise upon irradiation with a fixed proton flux (i.e., 6.5 × 10⁷ H⁺ s⁻¹ cm⁻²) at the beginning of the experiment, i.e., unirradiated device, and after fixed total proton irradiation (2 × 10¹⁰ H⁺ and 3 × 10¹⁰ H⁺). The yellowish region indicates the temporal window typical of a proton therapy run.