“n-Doping of a low-electron-affinity polymer used as an electron-transport layer in organic light-emitting diodes,” H.L. Smith, J.T. Dull, E. Longhi, S. Barlow, B.P. Rand, S.R. Marder, A. Kahn, Adv. Funct. Mater., 30, 2000328 (2020).