Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface
Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface
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DOI：
10.1021/jp512153b
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发表时间：
2015-03-05
影响因子：
3.7
通讯作者：
Monti, Oliver L. A.
中科院分区：
文献类型：
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作者：
Gruenewald, Marco;Schirra, Laura K.;Monti, Oliver L. A.
我们利用互补光学和电子能谱技术研究了PTCDA和导电n掺杂ZnO薄膜之间形成的典型杂化界面。我们证明了ZnO表面附近的浅层供体导致PTCDA的整数电荷转移，这显然局限于第一层单层。通过DFT计算，我们发现阴离子PTCDA的实验特征可以理解为与底物中的局域态（浅给体）强杂化和电荷回给；导致在界面上有效的整数电荷转移。因此，电荷转移不仅仅是将费米能级定位在PTCDA电子输运能级之上的问题，而是需要对界面相互作用有原子性的理解。研究表明，缺陷位置和掺杂剂对界面耦合特性有显著影响，从而影响载流子注入或萃取。
We investigate the prototypical hybrid interface formed between PTCDA and, conductive n-doped ZnO films by means of complementary optical and electronic spectroscopic techniques. We demonstrate that shallow donors in the vicinity of the ZnO surface cause an integer charge transfer to PTCDA, which is clearly restricted to the first monolayer. By means of DFT calculations, we show that the experimental signatures of the anionic PTCDA species can be understood in terms of Strong hybridization with localized states (the shallow donors) in the substrate and charge back-donation; resulting in an effectively integer charge transfer across the interface. Charge transfer is thus not merely a question of locating the Fermi level above the PTCDA electron-transport level but requires rather an atomistic understanding of the interfacial interactions. The study reveals that defect sites and dopants can have a significant influence on the specifics of interfacial coupling and thus on carrier injection or extraction.