Tuning hole-injection barriers at organic/metal interfaces exploiting the orientation of a molecular acceptor interlayer

摘要: Ultraviolet photoelectron spectroscopy was used to demonstrate organic/metal-contact charge injection barrier tuning by exploiting the orientation-dependent work function \ensuremath{\phi} of a molecular acceptor [hexaazatriphenylene-hexanitrile (HATCN)] interlayer on Ag(111). The flat-lying HATCN monolayer Ag 4.6 eV (similar pristine electrode), whereas layer edge-on exhibited 5.5 (comparable Au electrode). hole-injection barriers (HIBs) between HATCN-modified electrodes and organic semiconductors tris(8-hydroxyquinoline)aluminum (Alq${}_{3}$) N,N${}^{\ensuremath{'}}$-bis(1-naphtyhl)-N,N${}^{\ensuremath{'}}$-diphenyl-1,1${}^{\ensuremath{'}}$-biphenyl-4.4${}^{\ensuremath{'}}$-diamine (\ensuremath{\alpha}-NPD) were reduced more than 1 compared electrodes. Noteworthy, HIBs determined with lower those obtained for substrates (\ensuremath{\phi} both is eV), found ca. 5.4 eV). This shows that interlayers are beneficial in electronic devices even when molecularly modified electrode comparable metal surface. It argued electronically rigid their counterparts, i.e., electron spill-out at organic-terminated surface less pronounced surfaces.