While halide perovskite X-ray detectors based on single crystals could achieve extraordinary sensitivities, detectors based on polycrystalline thick films lag behind in efficiency. This is unfortunate since the processing methods for producing polycrystalline thick films, especially by pressure treatment of powders, are suitable for upscaling. Here, we investigate in detail the pressing of readily prepared powders of methylammonium lead halide perovskites MAPbI₃ and MAPbBr₃ to thick layers. By time-dependent pressure measurements, we monitor the occurring compaction dynamics, identifying two relaxation processes with different timescales. When pressing at elevated temperatures from room temperature (RT) to 100 °C, the pressure relaxations change drastically. While the layer properties such as relative density and surface roughness only improve to a certain degree by increasing the pressure at RT, we observe relative densities >97%, considerable reduction in surface roughness, and a significant increase in grain size with tempered pressing. Analyses regarding time-dependent pressure relaxations of tempered pressing allow attributing the dynamics to a sintering process, where we find the sinter onset to be surprisingly low at about 30 °C, mainly independent of the applied pressure (10–100 MPa). Our results will allow for an improved and more targeted powder processing of halide perovskite thick films as they are promising candidates for efficient X-ray detectors.

中文翻译：

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压力和温度对粉末压制甲基铵卤化铅厚膜压实动力学和层性能的影响

尽管基于单晶的钙钛矿卤化物X射线探测器可以实现非凡的灵敏度，但基于多晶厚膜的探测器却在效率上落后。这是不幸的，因为用于生产多晶厚膜的加工方法，特别是通过粉末的压力处理，适合于放大。在这里，我们详细研究了易于制备的甲基铵卤化铅钙钛矿MAPbI ₃和MAPbBr ₃粉末的压制厚层。通过与时间有关的压力测量，我们可以监视发生的压实动力学，确定具有不同时间尺度的两个松弛过程。在从室温（RT）到100°C的高温下加压时，压力松弛会急剧变化。尽管在室温下通过增加压力只能使涂层的相对密度和表面粗糙度等性能得到一定程度的改善，但我们观察到相对密度> 97％，表面粗糙度的显着降低以及回火压制后晶粒尺寸的显着增加。关于回火压力随时间变化的压力松弛的分析允许将动力学归因于烧结过程，在烧结过程中，我们发现烧结开始在30°C时出奇地低，主要与施加的压力（10-100 MPa）无关。