2, Lawrence Berkeley National Laboratory, Berkeley, California, United States
3, Stanford Synchrotron Radiation Laboratory, Menlo Park, California, United States
Solution-based processing of materials for electrical doping of organic semiconductor interfaces is attractive for boosting the efficiency of organic electronic devices with multilayer structures. To simplify this process, self-doping perylene diimide (PDI)-based ionene polymers were synthesized, combining semiconductor PDI components with electrolyte dopants embedded within the polymer backbone. Functionality contained within the PDI monomers suppressed their aggregation, affording self-doping interlayers with controllable thickness when processed from solution into organic photovoltaic devices (OPVs). Optimal results for interfacial self-doping led to increased power conversion efficiencies (PCEs) of the fullerene-based OPVs from 2.62% to 10.64%, and of the non-fullerene-based OPVs from 3.34% to 10.59%. These ionene interlayers enable chemical and morphological control of interfacial doping and charge transport, demonstrating that effective conductive channels are crucial for charge transport in doped organic semiconductor films. Using the interlayers with efficient doping and charge transport, both fullerene- and non-fullerene-based OPVs were achieved PCEs exceeding 9% over interlayer thicknesses ranging from ~3 to ~40 nm.