The quality and the stability of devices prepared from polycrystalline layers of organic–inorganic perovskites highly depend on the grain sizes prevailing. Tuning of the grain size is either done during layer preparation or in a post-processing step. Our investigation refers to thermal imprint as the post-processing step to induce grain growth in perovskite layers, offering the additional benefit of providing a flat surface for multi-layer devices. The material studied is MAPbBr₃; we investigate grain growth at a pressure of 100 bar and temperatures of up to 150 °C, a temperature range where the pressurized stamp is beneficial to avoid thermal degradation. Grain coarsening develops in a self-similar way, featuring a log-normal grain size distribution; categories like ‘normal’ or ‘secondary’ growth are less applicable as the layers feature a preferential orientation already before imprint-induced grain growth. The experiments are simulated with a capillary-based growth law; the respective parameters are determined experimentally, with an activation energy of Q ≈ 0.3 eV. It turns out that with imprint as well the main parameter relevant to grain growth is temperature; to induce grain growth in MAPbBr₃ within a reasonable processing time a temperature of 120 °C and beyond is advised. An analysis of the mechanical situation during imprint indicates a dominance of thermal stress. The minimization of elastic energy and surface energy together favours the development of grains with (100)-orientation in MaPbBr₃ layers. Furthermore, the experiments indicate that the purity of the materials used for layer preparation is a major factor to achieve large grains; however, a diligent and always similar preparation of the layer is equally important as it defines the pureness of the resulting perovskite layer, intimately connected with its capability to grow. The results are not only of interest to assess the potential of a layer with respect to grain growth when specific temperatures and times are chosen; they also help to rate the long-term stability of a layer under temperature loading, e.g. during the operation of a device.

由有机-无机钙钛矿多晶层制备的器件的质量和稳定性在很大程度上取决于主要的晶粒尺寸。晶粒尺寸的调整要么在层制备过程中完成，要么在后处理步骤中完成。我们的研究将热压印作为诱导钙钛矿层中晶粒生长的后处理步骤，为多层器件提供平坦表面提供了额外的好处。研究的材料是 MAPbBr ₃; 我们在 100 bar 的压力和高达 150 °C 的温度下研究晶粒生长，加压印模有利于避免热降解的温度范围。晶粒粗化以自相似的方式发展，具有对数正态晶粒尺寸分布；“正常”或“二次”生长等类别不太适用，因为这些层在压印诱导晶粒生长之前就已经具有优先取向。实验采用基于毛细管的生长规律进行模拟；各个参数通过实验确定，活化能为 Q ≈ 0.3 eV。事实证明，对于印记，与晶粒生长相关的主要参数是温度；在 MAPbBr _{3 中}诱导晶粒生长在合理的处理时间内，建议温度达到 120 °C 或更高。对压印期间机械状况的分析表明热应力占主导地位。弹性能和表面能的最小化有利于 MaPbBr _{3 中}具有 (100) 取向的晶粒的发展层。此外，实验表明用于层制备的材料的纯度是实现大晶粒的主要因素；然而，勤奋且始终相似的层制备同样重要，因为它定义了所得钙钛矿层的纯度，与其生长能力密切相关。结果不仅对于在选择特定温度和时间时评估层与晶粒生长的潜力有关；它们还有助于评估层在温度负载下的长期稳定性，例如在设备运行期间。