Fig. 4: Spectroscopic confirmation of doping.
From: A high-conductivity n-type polymeric ink for printed electronics
a Evolution of the work function measured by UPS and the spin density measured by EPR for BBL:PEIlin films with different PEI content. b Difference UV-Vis absorption spectra of BBL:PEIlin (50 wt%) showing the evolution of polaron absorption induced by the increased PEI content. c The corresponding difference FTIR absorption spectra of the same samples. The difference absorption spectra in b and c were obtained by subtracting the BBL spectrum from the BBL:PEIlin spectra after normalization at 575 nm and 1370 cm−1 for UV-Vis and FTIR, respectively. A similar analysis is reported in Supplementary Fig. 26 for BBL:PEIbra.
