Surface Energy-Driven Preferential Grain Growth of Metal Halide Perovskites: Effects of Nanoimprint Lithography Beyond Direct Patterning
Surface Energy-Driven Preferential Grain Growth of Metal Halide Perovskites: Effects of Nanoimprint Lithography Beyond Direct Patterning
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DOI：
10.1021/acsami.0c17655
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发表时间：
2021-01-21
影响因子：
9.5
通讯作者：
Gu, Qing
中科院分区：
文献类型：
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作者：
Moon, Jiyoung;Kwon, Sunah;Gu, Qing
有机-无机杂化卤化铅钙钛矿材料由于具有高结晶度、光滑形貌和良好取向的晶粒等优异性能，在光电器件领域引起了广泛关注。最近，研究表明，热纳米压印光刻（NIL）是一种有效的方法，不仅可以直接图案化，而且可以改善退火钙钛矿薄膜的形态，结晶度和晶体取向。然而，NIL对钙钛矿材料性能的积极影响背后的基本机制尚未被理解。在这项工作中，我们研究了钙钛矿晶粒生长的动力学与表面能计算的第一性原理密度泛函理论（DFT），并揭示了表面能驱动的优先晶粒生长过程中NIL，其中涉及限制晶粒生长在表面法线方向，异常晶粒生长，晶体学重新取向，和晶界迁移的多重过程，是材料质量提高的使能者。此外，我们开发了一种优化的NIL工艺，并通过将其用于钙钛矿发光电化学电池（PeLEC）架构中来证明其有效性，与没有NIL的PeLEC相比，我们观察到最大电流效率提高了四倍，亮度提高了两倍，在3.5V时达到最大电流效率0.07598cd/A，在4V时达到最大亮度1084 cd/m（2）。
Hybrid organic-inorganic lead halide perovskites have attracted much attention in the field of optoelectronic devices because of their desirable properties such as high crystallinity, smooth morphology, and well-oriented grains. Recently, it was shown that thermal nanoimprint lithography (NIL) is an effective method not only to directly pattern but also to improve the morphology, crystallinity, and crystallographic orientations of annealed perovskite films. However, the underlining mechanisms behind the positive effects of NIL on perovskite material properties have not been understood. In this work, we study the kinetics of perovskite grain growth with surface energy calculations by first-principles density functional theory (DFT) and reveal that the surface energy-driven preferential grain growth during NIL, which involves multiplex processes of restricted grain growth in the surface-normal direction, abnormal grain growth, crystallographic reorientation, and grain boundary migration, is the enabler of the material quality enhancement. Moreover, we develop an optimized NIL process and prove its effectiveness by employing it in a perovskite light-emitting electrochemical cell (PeLEC) architecture, in which we observe a fourfold enhancement of maximum current efficiency and twofold enhancement of luminance compared to a PeLEC without NIL, reaching a maximum current efficiency of 0.07598 cd/A at 3.5 V and luminance of 1084 cd/m(2) at 4 V.