Table 1.
Values of apparent work function, work function shift, the onset of the molecular HOMO energy measured using UPS, and the barrier obtained from fitting the data to a modified (19) form of the Simmons tunneling model. Data for PPF (2) from ref. 6
| Sample | WF (eV) | ΔWF | EHOMO,onset | ϕSimmons (eV) |
| PPF | 4.53 | — | — | — |
| PPF/EB | 4.40 | −0.13 | 1.4 ± 0.1 | 1.4 |
| PPF/BP | 4.53 | 0 | 1.7 ± 0.1 | — |
| PPF/ BrB | 4.88 | +0.35 | 1.5 ± 0.3 | 1.5 |
| PPF/ NP | 4.97 | +0.44 | 1.4 ± 0.2 | 1.0 |
| PPF/AB | 4.66 | +0.13 | 1.0 ± 0.1 | 1.2 |
| PPF/BTB | 4.41 | −0.12 | 1.2 ± 0.1 | 1.1 |
| PPF/1AQ | 4.56 | +0.03 | 1.3 ± 0.1 | 1.4 |
| PPF/2AQ | 4.43 | −0.1 | 1.4 ± 0.1 | 1.25 |
| PPF(2)(6) | 4.71 | — | — | — |
| PPF(2)/NAB(6) | 5.04 | +0.33 | 1.2 ± 0.1 | 1.1 |
| PPF(2)/FL(6) | 4.65 | −0.06 | 1.5 ± 0.1 | 1.3 |
| PPF(2)/Alkane(6) | 4.93 | +0.22 | 2.0 ± 0.1 | 1.8 |
| PPF/NAB | 5.07 | |||
| Au/NAB | 5.1 | |||
| Pt/NAB | 5.2 |