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利用自旋涂膜(spin-coating)技术在清洁的Si衬底表面制备出共轭聚合物薄膜(poly(9,9-di-n-hexylfluorenyl-2,7-vinylene),PDHFV)样品,利用同步辐射光电子能谱(SRPES)技术结合常规X射线光电子能谱(XPS)技术原位研究了Ca在PDHFV表面的沉积过程.在Ca的初始沉积阶段(<1.9ML),PDHFV薄膜中吸附的氧向界面聚集并与沉积的Ca发生反应;同时,C1s芯能级谱随Ca覆盖度增加而展宽,表明在该阶段聚合物中乙烯基上的C原子与沉积的Ca原子间发生强烈相互作用.当Ca的覆盖度从1.9ML增至5.4ML时,Ca原子主要与聚合物苯基中的C原子发生相互作用,并伴随着C1s峰向高结合能方向移动.整个界面形成过程中,没有出现明显的带隙态和电子注入势垒;通过与常规的聚烷基芴(poly(9,9-dioctylfluorene),PFO)比较发现,乙烯基的引入可以很好地抑制界面带隙态的出现,这对提高界面的复合发光效率非常有利.
A sample of poly (9,9-di-n-hexylfluorenyl-2,7-vinylene) (PDHFV) was prepared on a cleaned Si substrate by spin-coating technique. Synchrotron radiation photoelectron spectroscopy (SRPES) technique was used to study the deposition process of Ca on the surface of PDHFV by conventional X-ray photoelectron spectroscopy (XPS) .In the initial deposition stage of Ca (<1.9ML), oxygen adsorbed in PDHFV films At the same time, the energy spectrum of C1s core broadens with the increase of Ca coverage, indicating that there is a strong interaction between the C atoms on the vinyl and the Ca atoms in the polymer during this phase. When the Ca coverage increases from 1.9 to 5.4 ML, the Ca atom mainly interacts with the C atom in the phenyl group of the polymer and moves toward the high binding energy along with the C1s peak. The entire interface does not appear during the formation of the interface Obvious band gap and electron injection barrier. Comparing with conventional poly (9,9-dioctylfluorene) (PFO), we found that the introduction of vinyl can well suppress the occurrence of interface bandgap, This is very beneficial to improve the composite luminous efficiency of the interface.