“…Several studies claim that effective p-type doping occurs when the dopant lowest unoccupied molecular orbital (LUMO) level is deeper than the host highest occupied molecular orbital (HOMO) level in order to realize integer charge transfer. [9,17,18] 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) with its LUMO located at ~ 5.24 eV [19] should then be a strong p-type dopant upon mixing with the host polymers [9,17] (crystalline) regioregular poly(3-hexylthiophene) (rr-P3HT, HOMO ~ 4.65 eV) and (amorphous) poly [2,3- Several studies find that energy level alignment at organic/electrode and organic/organic interfaces plays a critical role in multilayer stack device, nearly dominating the performance. [20][21][22][23][24] Typically, the energy level alignment of such interfaces follows the trends predicted by the so-called integer charge transfer (ICT) model, i.e.…”