Density-Dependent Reorientation and Rehybridization of Chemisorbed Conjugated Molecules for Controlling Interface Electronic Structure

Abstract

The adsorption of the molecular acceptor hexaazatriphenylene-hexacarbonitrile on Ag(111) was investigated as function of layer density. We find that the orientation of the first molecular layer changes from a face-on to an edge-on conformation depending on layer density, facilitated through specific interactions of the peripheral molecular cyano groups with the metal. This is accompanied by a rehybridization of molecular and metal electronic states, which significantly modifies the interface and surface electronic properties, as rationalized by theoretical modeling.

Energy level alignment and interactive spin polarization at organic/ferromagnetic metal interfaces for organic spintronics

“…35,36 It could also be caused by a change in the molecular orientation as the surface is saturated, which in turn affects the work function, similar to the case reported for hexaazatriphenylenehexacarbonitrile molecules chemisorbed on Ag(111). 37 The situation for AOB deposited on Fe, presented in Figure 2, is quite different compared with that of TCNQ. No hybrid state appears at the molecule/Fe interface and the frontier occupied electronic structure of the monolayer is the same as that of the bulk, showing the interaction between AOB and Fe is not as strong as that of TCNQ and Fe, but rather likely undergo physisorption.…”

The Molecularly Controlled Synthesis of Ordered Bi‐dimensional C60 Arrays

“…The dispersion was diluted to a given concentration with pure water before being used as a subphase in the Langmuir-Schaefer deposition. Dimethyldioctadecylammonium (DODA) bromide (purity > 99 %, Sigma-Aldrich) was used as received (structural formula [{CH 3 …”

“…DODA was dissolved (0.1 mg mL À1 ) in a mixture of HPLC-grade CHCl 3 and MeOH (9:1, v/v) to prepare the spreading solution. For surface modification, a mixture of EtOH and pure water (8:2, v/v) of DODA (0.5 mg mL À1 ) was used.…”

“…[2,11,[21][22][23][24][25][26][27]29] Thin films that were grown by deposition under ultrahigh vacuum are a much-exploited example of this behavior in which the initial monolayer maximizes the van der Waals and Coulomb forces to produce flat adsorption, whilst the subsequent deposition often makes molecules stand up. [3] However, islanding, which results in both 2D and 3D arrangements, is not easily avoidable with this fabrication method.…”

Inhibition of solution-processed 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile crystallization by mixing additives for hole injection layers in organic light-emitting devices

“…To date, various HILs have been reported, [4][5][6][7][8][9][10][11][12][13][14][15] and, among these, 1,4,5,8,9, 11-hexaazatriphenylene-hexacarbonitrile (HAT-CN) has been employed in HILs (leading to low driving voltage) 4,[16][17][18][19][20][21][22] since the first application of OLED by LG Chemical Ltd. 22 HAT-CN was first reported by Czarnik and co-workers 23 and its characterization has been investigated in various studies. [24][25][26][27][28][29] The most remarkable property of HAT-CN is the extremely deep energy level of its lowest unoccupied molecular orbital. Six nitrile groups attached to a heterocyclic moiety generate a large electron withdrawal effect from the heterocycle, making it a strong acceptor.…”