As a novel low-cost semiconductor with extraordinary photoelectric property, the inorganic CsPbX₃ perovskites have become emerging materials for the next generation of X-ray detectors in the past decade. However, most of recent studies of CsPbX₃ perovskites X-ray detectors are based on their internal photoelectric effect. Though it is also important and widely applied in vacuum X-ray detectors, the external photoelectric effect of CsPbX₃ perovskites has been barely studied by now. Thus, the response sensitivity of the CsPbX₃ perovskites external photoelectric effect in the X-ray region is studied in present paper. First, a 230 nm CsPbI₂Br membrane is prepared on a metal substrate via a conventional one-step deposition method with a precursor solution. Then the external photoelectric responsivity and quantum efficiency of the CsPbI₂Br membrane have been calibrated in the region from 2000 eV to 5500 eV at Beijing Synchrotron Radiation Facility. The responsivity is over 5.1×10^-5 A/W in the region and the quantum efficiency is over 23%. These calibration data are close to those of a traditional X-ray photoelectric material CsI. A Monte-Carlo method is utilized to simulate the external photoelectric effect of CsPbI₂Br perovskites, and the external photoelectric responsivity has been calculated. The calculated data match well with the calibration, and this prove the Monte-Carlo method feasible for the external photoelectric effect simulation of CsPbX₃ perovskites. Then the external photoelectric responsivities and quantum efficiencies of CsPbX₃ perovskites are calculated via the Monte-Carlo method in the X-ray region from 2000 eV to 10000 eV. The calculated responsivities of different CsPbX₃ perovskites are all closed to the responsivity of CsI, and an order of magnitude higher than that of Au, and there is a similar discipline of the CsPbX₃ quantum efficiencies. This indicates that CsPbX₃ perovskites have good external photoelectric properties and are potential for X-ray vacuum detectors such as photocathode and photomultiplier. The influence of thickness on CsPbX₃ photoelectric response has also been studied in this paper via MC simulation. The results show that the responsivities increase with the thickness due to the increasing X-ray absorption. The responsivities all reach their upper limits at about the thickness of 150 nm, which means the electrons generated at 150 nm can hardly escape from the material surface. It's indicated that the thickness of CsPbX₃ should be no less than 150 nm to get the optimal photoelectric response.
 

CsPbX3,高能X射线