Fig. 4.

Linking doping freeze-out and ICTC occupation. a–c Numerical solutions of the neutrality condition Eq. (4) for E_CT^b = 0.64 eV and N_V = 2.4 × 10¹⁹ cm⁻³. d Doping efficiencies p/N_A determined by incremental UPS on Ag/MeO-TPD(0.7 nm)/ZnPc(4.5 nm)/ZnPc:F₆-TCNNQ(x,MR) samples and fraction of ionized acceptors N_A⁻/N_A (F₆-TCNNQ⁻/F₆-TCNNQ) estimated from the absorption spectra of Fig. 2. Continuous lines indicate calculations using a three-level model with E_CT^b = 0.64 eV, E_A = 0.25 eV, and σ_CT = σ_A = σ_V = 160 meV, considering trap filling¹⁰