Fassl Paul, Ternes Simon, Lami Vincent, Zakharko Yuriy, Heimfarth Daniel, Hopkinson Paul E, Paulus Fabian, Taylor Alexander D, Zaumseil Jana, Vaynzof Yana
ACS Appl Mater Interfaces. 2019 Jan 16;11(2):2490-2499. doi: 10.1021/acsami.8b16460. Epub 2019 Jan 2.
In this work, we examine the effect of microstructure on ion-migration-induced photoluminescence (PL) quenching in methylammonium lead iodide perovskite films. Thin films were fabricated by two methods: spin-coating, which results in randomly oriented perovskite grains, and zone-casting, which results in aligned grains. As an external bias is applied to these films, migration of ions causes a quenching of the PL signal in the vicinity of the anode. The evolution of this PL-quenched zone is less uniform in the spin-coated devices than in the zone-cast ones, suggesting that the relative orientation of the crystal grains plays a significant role in the migration of ions within polycrystalline perovskite. We simulate this effect via a simple Ising model of ionic motion across grains in the perovskite thin film. The results of this simulation align closely with the observed experimental results, further solidifying the correlation between crystal grain orientation and the rate of ionic transport.
在这项工作中，我们研究了微观结构对甲脒碘化铅钙钛矿薄膜中离子迁移诱导的光致发光（PL）猝灭的影响。薄膜通过两种方法制备：旋涂法，可得到随机取向的钙钛矿晶粒；区域浇铸法，可得到取向排列的晶粒。当对这些薄膜施加外部偏压时，离子迁移会导致阳极附近的PL信号猝灭。与区域浇铸器件相比，旋涂器件中这种PL猝灭区的演变不太均匀，这表明晶粒的相对取向在多晶钙钛矿中的离子迁移中起着重要作用。我们通过一个简单的伊辛模型来模拟钙钛矿薄膜中离子跨晶粒的运动效应。该模拟结果与观察到的实验结果紧密吻合，进一步证实了晶粒取向与离子传输速率之间的相关性。
