Extended Data Figure 4: Characterization of selected self-compensated, heavily doped polymers.
From: Doped polymer semiconductors with ultrahigh and ultralow work functions for ohmic contacts
a–d, Triarylamine–fluorene copolymer P1. a, Optical spectra of doped P1 in solution (top), and of a P1 film before and after doping (bottom). For solution-state doping, 0.12 mM r.u. P1 in propylene carbonate was doped with NOSbF6 and self-compensated, yielding a final doping level of 0.5 holes per r.u. The optical spectrum is collected in a cell with a 2.0-mm path length. For film-state doping, a 100-nm-thick P1 film was doped with NOSbF6 and self-compensated, yielding a final doping level of 0.9 holes per r.u. b, c, UPS (b) and XPS spectra (c; N1s and F1s) of undoped and doped P1 (x ≈ 0.5) films. d, FTIR evidence for full self-compensation in a P1 film. Spectra were acquired before doping (red), after film-state doping with 6 mM NOSbF6 in acetonitrile (green) and after self-compensation by excess ion removal (Na+ and SbF6−) via spin-rinse with acetonitrile (blue). Infrared active vibration modes (IRAV; 1,100–1,600 cm−1) indicate that the film is doped. SbF6− (anti-symmetric stretching frequency νas = 660 cm–1) is present before, but not after, self-compensation (residual, <1%). e–g, Naphthalenetetracarboxydiimide–thiophene copolymer N1. e, Optical spectra of doped N1 in solution (top), and of an N1 film before and after doping (bottom). For, solution-state doping, 0.22 mM r.u. N1 in dimethylsulfoxide was doped with sodium 9,10-diphenylanthracenide and self-compensated, yielding a final doping level of 1.0 electrons per r.u. The optical spectrum is collected in a cell with a 2.0-mm path length. For film-state doping, a 25-nm-thick N1 film was doped with sodium 9,10-diphenylanthracenide and self-compensated, yielding a final doping level of 1.0 electrons per r.u. f, g, UPS (f) and XPS spectra (g; N1s and I3d5/2) of undoped and doped N1 (x ≈ 1.0) films. h–k, Fluorene copolymers N2 and N3. h, i, Optical spectra of 40-nm-thick N2 (h) and N3 (i) films, before and after film-state doping with sodium naphthalenide solution and spin-rinsing with tetrahydrofuran. Final doping levels, 0.9 electrons per r.u. (N2; h) and 0.4 electrons per r.u. (N3; i). j, k, UPS spectra of undoped and n-doped N2 (j) and N3 (k) films. All binding energies are referenced to vacuum level. The Fermi energy EF is marked for doped films; the ionization potential IP is marked for undoped films.
