Highly stable and sensitive polystyrene/carbon black-BiI3 composite for direct X-ray detector

Sensitive and stable defect tolerant detectors with a long life, operating at low bias are essential for portable medical and security applications. Low-cost Polymer-high Z composite with conductive fillers show enhanced charge transportation and better long-term stability compared to conventional direct X-ray detector materials. Here, we report Polystyrene-Bismuth triiodide composite with carbon black incorporated as conductive filler. The composite showed great tolerance towards radiation induced structural damage as confirmed with XRD studies of pre and post irradiated samples. Also, the radiation induced defects in the composite due to continuous irradiation of X-rays have been studied with variation in thickness. In traditional planar detector configuration, photon absorption efficiency is defined by the thickness of the material, however as a downside, it limits the charge transport properties affected by traps in the chosen material. Therefore, a trade-off must be found between photon absorption efficiency and charge collection efficiency The detector shows low dark current density of 0.5 nA/cm(2) and high sensitivity of 0.6 x 10(3) & mu;C/Gy-cm(3) against dose rate of 500 & mu;-Gy/sec. at 30 V bias. In addition, the stability test exhibits no deterioration in sensing for integrated dose of 3200 mGy in one run which is 32,000 times the dose used in chest X-rays. In addition, the sample fully recovers its charge collection ability and neutralizes the space charge accumulation due to continuous irradiation illustrating longevity of the sample. The composite shows intriguing results as a promising material for low-bias, portable detector with high stability for X-ray imaging and detection applications.

Automated summary

Sensitive and stable defect tolerant detectors with a long life, operating at low bias are essential for portable medical and security applications. Low-cost Polymer-high Z composite with conductive fillers show enhanced charge transportation and better long-term stability compared to conventional direct X-ray detector materials. This study reports a Polystyrene-Bismuth triiodide composite with carbon black incorporated as conductive filler, which exhibits great tolerance towards radiation induced structural damage as well as excellent charge collection efficiency. The composite shows promising potential as a low-bias, portable detector with high stability for X-ray imaging and detection applications.