Kang Wen-Lu, Tsai Yi-Ting, Ji Yan-Cheng, Yi Rong-Huei, Wang Yun-Xin, Shen Hsiang-Ling, Chen Xuan-Jun, Hsu Yu-Cheng, Lu Chin-Wei, Yang Zu-Po, Su Hai-Ching
Institute of Lighting and Energy Photonics, National Yang Ming Chiao Tung University, Tainan, 71150, Taiwan.
Institute of Photonic System, National Yang Ming Chiao Tung University, Tainan, 71150, Taiwan.
Chemistry. 2021 Dec 20;27(71):17785-17793. doi: 10.1002/chem.202103739. Epub 2021 Nov 29.
Recently, perovskites have attracted intense attention due to their high potential in optoelectronic applications. Employing perovskites as the emissive materials of light-emitting electrochemical cells (LECs) shows the advantages of simple fabrication process, low-voltage operation, and compatibility with inert electrodes, along with saturated electroluminescence (EL) emission. Unlike in previously reported perovskite LECs, in which salts are incorporated in the emissive layer, the ion-transport layer was separated from the emissive layer in this work. The layer of ionic transition metal complex (iTMC) not only provides mobile ions but also serves as an electron-injection/transport layer. Orthogonal solvents are used in spin coating to prevent the intermixing of stacked perovskite and iTMC layers. The blue iTMC with high ionization potential is effective in blocking holes from the emissive layer and thus ensures EL color saturation. In addition, the carrier balance of the perovskite/iTMC LECs can be optimized by adjusting the iTMC layer thickness. The optimized external quantum efficiency of the CsPbBr /iTMC LEC reaches 6.8 %, which is among the highest reported values for perovskite LECs. This work successfully demonstrates that, compared with mixing all components in a single emissive layer, separating the layer of ion transport, electron injection and transport from the perovskite emissive layer is more effective in adjusting device carrier balance. As such, solution-processable perovskite/iTMC LECs open up a new way to realize efficient perovskite LECs.
最近，钙钛矿因其在光电应用中的巨大潜力而备受关注。将钙钛矿用作发光电化学电池（LEC）的发光材料具有制备工艺简单、低电压运行以及与惰性电极兼容性好等优点，同时还能实现饱和电致发光（EL）发射。与之前报道的将盐掺入发光层的钙钛矿LEC不同，在本工作中离子传输层与发光层是分离的。离子型过渡金属配合物（iTMC）层不仅提供可移动离子，还作为电子注入/传输层。旋涂过程中使用正交溶剂以防止堆叠的钙钛矿层和iTMC层相互混合。具有高电离势的蓝色iTMC能有效阻挡来自发光层的空穴，从而确保EL颜色饱和度。此外，通过调整iTMC层厚度可以优化钙钛矿/iTMC LEC的载流子平衡。CsPbBr /iTMC LEC优化后的外量子效率达到6.8%，这是钙钛矿LEC报道的最高值之一。这项工作成功证明，与在单个发光层中混合所有组分相比，将离子传输、电子注入和传输层与钙钛矿发光层分离在调节器件载流子平衡方面更有效。因此，可溶液加工的钙钛矿/iTMC LEC为实现高效钙钛矿LEC开辟了一条新途径。
