Researchers from KU Leuven in Belgium have demonstrated a promising direct X-ray detector design, based on a Cs2AgBiBr6 halide perovskite semiconductor. This perovskite is said to be ideal for direct X-ray conversion because of its ability to combine silver (Ag) and bismuth (Bi) heavy atomic nuclei – for efficient X-ray absorption – with their excellent charge formation and transport properties.
The researchers pointed out the all-inorganic double metal halide perovskite Cs2AgBiBr6 as one of the strongest candidates because of its high X-ray sensitivity and excellent structural stability. By optimizing the materials and lowering the operating temperature, they were even able to improve the X-ray sensitivity of the device tenfold, ultimately peaking near 500 times more sensitive than commercial direct conversion X-ray detectors on the market – commonly based on pure selenium (Se).
Importantly, the researchers studied their detector at both room and low temperatures to track physical features that are beneficial for the efficient conversion of X-rays into a collectible signal. This is an extremely novel approach, and one that offers a generic method for screening other potentially good X-ray detecting mediums. Using this method, the researchers developed an extensive photo-physical model to account for the large jump in X-ray sensitivity when operating at reduced temperatures.
This research can be viewed as a step forward in the development of new, cheap and easy to make X-ray detectors based on perovskite semiconductors and the possible applications are numerous.