Figure 3 : Impact of effective substrate work function on band bending and barriers.

From: Organic semiconductor density of states controls the energy level alignment at electrode interfaces

Figure 3

(a) Total electron potential energy change −eV(d) across pentacene films of varying thickness d for a series of Fermi level energies ranging from 0.15 eV below EL, the initial LUMO peak energy (top trace), to 0.05 eV above EH, the initial HOMO peak energy (bottom trace). (b) Data from a converted to injection barriers Δe for electrons (left axis) and Δh for holes (right axis). Dashed horizontal lines indicate respective values of zero and the vertical line highlights the cut visualized in c. (c) Injection barriers Δe (left axis) and Δh (right axis) as a function of effective substrate work function Φeff for a d=10 nm thick pentacene film with (·) and without () polaronic relaxation energies λ+ (for holes) and λ (for electrons) taken into account. The transitions between the regions with slope S=0 and S=1 mark the so-called pinning work functions, Φ for LUMO pinning and Φ+ for HOMO pinning. The lowest achievable injection barriers are not related to λ+/−.