397 / 2019-02-28 17:36:46

Efficient detection of X-ray photons based on solution- synthesized perovskites

X-ray response, perovskites, photodetector

全体主题 > Laser and Particle Beam Fusion

Much attention has been paid to the detection of X-ray photons owing to its potential applications, such as crystal structure determination, industrial material inspection, scientific research in the fields of matter and radiation at extremes, and so on. Two approaches to the X-ray photon detection are available. One is the indirect conversion of high-energy X-ray photons into visible light using scintillators and the other is the direct conversion of X-ray photons into electrical current signals. The direct conversion is easily achieved using materials with high photo-conversion efficiency. Solution-synthesized metal halide semiconductors usually applied in photovoltaic and photoconductive devices would provide an alternative way for efficient X-ray photon detection. Here we report on the X-ray responses of photodetector based on inorganic CsPbBr3 nanoparticles or hybrid lead halide perovskite (CH3NH3PbI3-XClX).
(1) A significant enhancement of X-ray photon response is demonstrated by loading CsPbBr3 nanoparticles with an even distribution onto rGO surface. Clear conductive switching phenomenon with a state conversion between “on” and “off” is observed under the intermittent X-ray exposure. These results provide a new potential application of CsPbBr3/rGO nanocomposites for X-ray photon detection.
(2) Based on hybrid halide perovskite, we prepared the detectors with a layered structure. The short-circuit photocurrent under visible light clearly exhibits distinct on/off states with a switching ratio higher than 10^4. From the transient photovoltage curve the carrier recombination lifetime is extracted to be 28 ms, which suggests a long carrier diffusion length. This characteristic can be directly applied in X-ray detection. The X-ray current density shows a linear dependency on the dose rate. This detector has a high sensitivity, which is more than one order of magnitude larger than that of previously reported CH3NH3PbI3 perovskite films and comparable to that of CH3NH3PbBr3 single crystals. Moreover, the X-ray currents still behave steadily with almost no change in amplitude after preserved for 10 days.