Oct 9 2019
NUS scientists have reported in自然（（26September) the discovery of latent universal electron donors from common anions, like oxalate, which can potently transfer electrons to organic semiconductors, realising the dream to achieve electron injection layers with ultralow work functions which can yet be processed from solution in the ambient.
图像显示了孔（左）和电子注射（右）材料的Koh Qi-mian Holding溶液样品，这些样品准备在环境中进行解决方案处理，以制造半导体设备的电极。欧洲杯足球竞彩
This is expected to open many new possibilities, not only for organic electronics, but also other advanced semiconductors, including quantum dots, nanowires, two-dimensional (2D) materials, and perovskites.
材料的工作函数是去除真空的最小紧密结合电子所需的最小能量。这决定了该材料将电子注入半导体的能力。电子注入层需要足够低的工作功能，最好小于4个电子伏特，才能有效地从许多新型半导体中注入（和收集）电子。但是，这通常需要在真空条件下蒸发反应性金属的薄膜，这限制了设备架构，加工性和制造性。超级工作功能材料会因暴露于空气而降低。欧洲杯足球竞彩
Now, the Chemistry team led by Prof Lay-Lay CHUA, and Physics teams led by Dr Rui-Qi PNG and Prof Peter HO, from the Organic Nano Device Laboratory, NUS have demonstrated that multivalent anions, such as oxalate, carbonate and sulfite, can act as powerful latent electron donors, when they are dispersed as small ion clusters in a polymer matrix of suitable conjugate polyelectrolytes. Conjugated polyelectrolytes are polymers with ionic side groups and delocalised electrons in the backbone. Crucially, the mixture can be processed from solution in air, and the anion spontaneously transfers electrons to the polymer host only after drying, thereby serendipitously protecting the material from atmospheric degradation. With the appropriate polyelectrolyte host, work functions as low as 2.4 electron-volts have been attained, overcoming the long-standing conundrum to marry ultralow work function materials with solution processing. The research team has demonstrated the versatility of this discovery by making a variety of high-performance white-light-emitting diodes and organic solar cells using solution-processed electron-injection layers.
“与前体掺杂剂不同，这些阴离子不需要化学转化才能变得活跃”PNG博士解释说。“They work because the repulsion between electrons in these anions causes their electron donor level to remain high, even in the solid state, when they become dehydrated. Together with careful design of the polyelectrolyte host, we can achieve ultralow work function materials previously not thought possible.”
Prof Chua said,“这项工作扩展了我们三年前开创的自我补偿的掺杂聚合物平台。”她补充说：“可以利用如此简单的阴离子来完成过去二十年来一直是这个领域的圣杯！”
The teams are currently working with industry and academic partners to extend the approach to other types of devices, and to establish the technology.
The research was performed in collaboration with Cambridge Display Technology Ltd (CDT), a subsidiary of Sumitomo Chemical Co., Ltd (SCC).
参考
Tang CG; Syafiqah MN; Koh QM; Zhao C; Zaini J; Seah QJ; Cass MJ; Humphries MJ; Grizzi I; Burroughes JH; Png RQ*; Chua LL*; Ho PKH, “Multivalent anions as universal latent electron donors” NATURE Volume: 573 Page Number: 519-525 DOI: 10.1038/s41586-019-1575-7 Published: 2019.
Source:http://www.nus.edu.sg/