Understanding the Improvement in the Stability of a Self-Assembled Multiple-Quantum Well Perovskite Light-Emitting Diode

We fabricate two-dimensional Ruddlesden-Popper layered perovskite films by introducing 1-naphthylmethylamine iodide into the precursor, which forms a self-assembled multiple-quantum well (MQW) structure. Enabling outstanding electroluminescence properties, light-emitting diodes (LEDs) using the MQW structure also demonstrate significant improvement in stability in comparison with the stability of devices made from formamidinium lead iodide. To understand this, we perform electro-absorption spectroscopy, wide-field photoluminescence imaging microscopy and impedance spectroscopy. Our approach enables us to determine the mobility of iodide ions in MQW perovskites to be (1.5 +/- 0.8) X 10(-8) cm(2) V(-1)s(-1), similar to 2 orders of magnitude lower than that in three-dimensional perovskites. We highlight that activated ion migration is a requirement for a degradation pathway in which a steady supply of ions is needed to modify the perovskite/external contact interfaces. Therefore, the improvement in stability in a MQW perovskite LED is directly attributed to the suppressed ion migration due to the inserted organic layer acting as a barrier for ionic movement.

我们通过在前驱体中引入1 - 萘甲胺碘化物来制备二维Ruddlesden - Popper层状钙钛矿薄膜，其形成了一种自组装多量子阱（MQW）结构。采用MQW结构的发光二极管（LED）具有出色的电致发光性能，并且与由甲脒碘化铅制成的器件的稳定性相比，其稳定性也有显著提高。为了理解这一点，我们进行了电吸收光谱、宽场光致发光成像显微镜和阻抗光谱分析。我们的方法使我们能够确定MQW钙钛矿中碘离子的迁移率为(1.5 ± 0.8)×10⁻⁸ cm² V⁻¹ s⁻¹，比三维钙钛矿中的迁移率低约两个数量级。我们强调，活化的离子迁移是一种降解途径所必需的，在这种降解途径中，需要稳定供应离子来改变钙钛矿/外部接触界面。因此，MQW钙钛矿LED稳定性的提高直接归因于插入的有机层作为离子移动的屏障抑制了离子迁移。