Lead-free perovskites for X-ray detecting.
Lead-free perovskites for X-ray detecting.
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DOI：
10.1016/j.scib.2017.10.013
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发表时间：
2017-10
期刊：
影响因子：
18.9
通讯作者：
F. Zhuge;Peng Luo;T. Zhai
中科院分区：
文献类型：
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作者：
F. Zhuge;Peng Luo;T. Zhai
X射线检测对于计算机断层扫描、安全检查、工业产品的无损检测和其他检测应用非常重要[1，2]。由于X射线检查可能导致癌症，因此始终存在实现具有更高灵敏度和检测限的X射线探测器的空间。有两种可用的方法检测X射线，第一种是间接转换，使用放大器将X射线光子转换为光，然后使用光电二极管将光转换为电荷;另一种是将X射线光子直接转换为电流[3]。基于闪烁器的探测器的缺点是有源层中的光散射，从而导致图像模糊[4]。通过非晶或晶体半导体的直接转换有效地克服了这样的缺点，并且由于更简单的系统配置，还能够实现高灵敏度和低检测限[5]。适用于直接转换X射线探测的半导体应具有：（1）高密度和高原子序数，因为吸收系数为a/Z4/E3，其中Z和E分别表示材料的原子序数和辐射能量;（2）载流子迁移率和寿命的高ls乘积，用于有效的电荷收集;（3）高电阻率，以抑制噪声电流;（4）长期工作的良好稳定性[3]。因此，研究最多的用于直接转换X射线探测的半导体是a-Se、HgI 2和CdZnTe。基于a-Se的探测器已商业化用于乳房X光检查、普通X光检查和荧光透视[6]。然而，主要缺点是由于其低衰减效率，其对高能X射线的量子效率低[7]。对于HgI 2和CdZnTe，Hg和Cd的毒性以及难以在薄膜晶体管（TFT）阵列上沉积均匀的薄膜是其应用的主要限制，近年来，有机-无机混合卤化铅钙钛矿作为一种优异的光伏材料也被开发用于X射线探测，因为其具有高的X射线衰减效率、高的LS乘积、单晶（SC）的低成本溶液生长和沉积均匀膜的便利性[8，9]。Han，Park及其同事[10]最近报道了一种10 cm × 10 cm平板X射线探测器，可从可打印的CH 3 NH3 PbI 3中获得低剂量X射线成像。尽管卤化铅钙钛矿在X射线探测方面取得了显著进展，但仍存在一些剩余的挑战
X-ray detection is of great importance for computed tomography scanning, security inspection, non-destructive testing of industrial products and other detection applications [1, 2]. Due to the potential cancer risk caused by X-ray inspection, there is always room to achieve X-ray detectors with even better sensitivity and detection limit. There are two available approaches detecting X-rays, the first is indirect conversion using scintillators to convert X-ray photons into light and then a photodiode to convert light into charges; the other is direct conversion of X-ray photons into electrical current [3]. The drawback of scintillator-based detectors is the light scattering in active layer and thereby image blurring [4]. The direct conversion through amorphous or crystalline semiconductors effectively overcomes such shortcoming, and also enables high sensitivity and low detection limit due to a simpler system configuration [5]. Suitable semiconductors for the direct conversion X-ray detection should have:(1) high density and high atomic number, since absorption coefficient a/Z4/E3, where Z and E denote respectively the atomic number of material and the radiation energy;(2) high ls product of the carrier mobility and lifetime for efficient charge collection;(3) high resistivity to suppress the noise current;(4) good stability for long-term operation [3]. Thereby, the most studied semiconductors for direct conversion X-ray detecting are a-Se, HgI2 and CdZnTe. Detectors based on a-Se have been commercialized for mammography, general radiography and fluoroscopy [6]. The main drawback, however, is its low quantum efficiency for high-energy X-rays due to its low attenuation efficiency [7]. As for HgI2 and CdZnTe, the toxicity of Hg and Cd, as well as the difficulty in depositing a uniform film onto the thin-film transistors (TFT) arrays are the main limitations in applications.Recent years, organic-inorganic hybrid lead halide perovskites, which have been demonstrated as an exceptional photovoltaic material, are also developed for X-ray detection because of their high X-ray attenuation efficiency, high ls product, low-cost solution growth of single crystals (SCs) and convenience of depositing uniform films [8, 9]. Han, Park and co-workers [10] recently reported a 10 cm  10 cm flat panel X-ray detectors from printable CH3NH3PbI3 to obtain low-dose X-ray imaging. Although lead halide perovskites have made remarkable progress in X-ray detection, there are still some remaining challenges