工作职能
半导体
兴奋剂
电子亲和性(数据页)
化学
离子键合
材料科学
离子
电子
欧姆接触
化学物理
光电子学
电子转移
电极
分子
纳米技术
光化学
有机化学
物理化学
物理
量子力学
作者
Cindy G. Tang,Mazlan Nur Syafiqah,Qi‐Mian Koh,Chao Zhao,Zaini Jamal,Qiu‐Jing Seah,Michael Cass,Martin J. Humphries,Ilaria Grizzi,J. H. Burroughes,Rui‐Qi Png,Lay‐Lay Chua,Peter K. H. Ho
出处
期刊:Nature
[Springer Nature]
日期:2019-09-25
卷期号:573 (7775): 519-525
被引量:56
标识
DOI:10.1038/s41586-019-1575-7
摘要
Electrodes with low work functions are required to efficiently inject electrons into semiconductor devices. However, when the work function drops below about 4 electronvolts, the electrode suffers oxidation in air, which prevents its fabrication in ambient conditions. Here we show that multivalent anions such as oxalate, carbonate and sulfite can act as powerful latent electron donors when dispersed as small ion clusters in a matrix, while retaining their ability to be processed in solution in ambient conditions. The anions in these clusters can even n-dope the semiconductor core of π-conjugated polyelectrolytes that have low electron affinities, through a ground-state doping mechanism that is further amplified by a hole-sensitized or photosensitized mechanism in the device. A theoretical analysis of donor levels of these anions reveals that they are favourably upshifted from ionic lattices by a decrease in the Coulomb stabilization of small ion clusters, and by irreversibility effects. We attain an ultralow effective work function of 2.4 electronvolts with the polyfluorene core. We realize high-performance, solution-processed, white-light-emitting diodes and organic solar cells using polymer electron injection layers with these universal anion donors, demonstrating a general approach to chemically designed and ambient-processed Ohmic electron contacts for semiconductor devices. Multivalent anions are found to be capable of electron-doping polymer semiconductors to realize conductive films with very low work functions, which enable efficient electron injection into materials with low electron affinity.
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