Upgrading of methylammonium lead halide perovskite layers by thermal imprint
Upgrading of methylammonium lead halide perovskite layers by thermal imprint
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DOI：
10.1007/s00339-021-04366-3
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发表时间：
2021-04-01
影响因子：
2.7
通讯作者：
Scheer, Hella-Christin
中科院分区：
文献类型：
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作者：
Mayer, Andre;Pourdavoud, Neda;Scheer, Hella-Christin
以甲基铵为基础的钙钛矿制造设备需要可靠和可扩展的加工。由于溶剂工程不是在大面积上获得均匀层的选择，我们的想法是通过在热压印步骤（称为“平面热压”）中再结晶来“升级”不完美的原始层，从而减少对层形成本身的需求。最近，压印已经证明了其改善钙钛矿层晶体尺寸的能力和大面积制造的可用性。我们从传统溶液制程获得的甲基溴化铅层开始。醋酸盐被用作有竞争力的铅源；即使在完美的条件下，所得到的钙钛矿层也会含有除所需钙钛矿外的副产物。根据所涉及的材料的物理性质，我们讨论了在软烘烤和热压印期间温度对层状态的影响。通过使用一种称为“热加载”的特殊压印技术，我们能够可视化该层随时间的升级，即晶粒的生长和晶粒边界处副产物的积累。通过随后的真空暴露，我们发现了非钙钛矿成分的存在，并对层的形貌进行了简单的检查；所有的实验都有x射线和电子衍射测量的支持。除降解外，我们还讨论了再结晶，并提出了后结晶来解释实验结果。这种通过后处理获得大颗粒钙钛矿层的物理方法是为器件制造大面积制备高质量层的关键一步。
The manufacturing of devices from methylammonium-based perovskites asks for reliable and scalable processing. As solvent engineering is not the option of choice to obtain homogeneous layers on large areas, our idea is to 'upgrade' a non-perfect pristine layer by recrystallization in a thermal imprint step (called 'planar hot pressing') and thus to reduce the demands on the layer formation itself. Recently, imprint has proven both its capability to improve the crystal size of perovskite layers and its usability for large area manufacturing. We start with methylammonium lead bromide layers obtained from a conventional solution-based process. Acetate is used as a competitive lead source; even under perfect conditions the resulting perovskite layer then will contain side-products due to layer formation besides the desired perovskite. Based on the physical properties of the materials involved we discuss the impact of the temperature on the status of the layer both during soft-bake and during thermal imprint. By using a special imprint technique called 'hot loading' we are able to visualize the upgrade of the layer with time, namely a growth of the grains and an accumulation of the side-products at the grain boundaries. By means of a subsequent vacuum exposition we reveal the presence of non-perovskite components with a simple inspection of the morphology of the layer; all experiments are supported by X-ray and electron diffraction measurements. Besides degradation, we discuss recrystallization and propose post-crystallization to explain the experimental results. This physical approach towards perovskite layers with large grains by post-processing is a key step towards large-area preparation of high-quality layers for device manufacturing.