A simply prepared amine oxide molecule as a low work function cathode modifier in organic photovoltaics for harvesting ambient light

Organic photovoltaics (OPV) that possibly convert ambient lights to electric energy are under the spotlight as a power supplier for portable, wearable, and Internet of Things devices. In order to enable the commercialization of ambient light harvesters, it is imperative to design and synthesize device components that offer cost-effectiveness, uniform deposition, and efficient charge extraction/collection. Here, we introduce a simple cathode interlayer (CIL) named EtNO for OPV-based ambient light harvesters. EtNO is designed with a chemical structure that does not require complicated conjugated units and is synthesized through a one-step procedure. EtNO CIL shows efficient reductions in the work function of electrodes, attributed to an interfacial dipole induced from an interaction between amine oxide group of EtNO and electrodes. Furthermore, EtNO forms a uniform layer through solution-processing without deteriorative effects on the surface of photoactive layer in OPVs. Therefore, the OPV with EtNO CIL exhibits an improved performance with an output power density of 79.2 μW cm–2 under light emitting diode illumination (1000 lx, 254 μW cm–2) compared to the device with conventional PDINO CIL (73.1 μW cm–2). Studies conducted on OPVs under halogen light illumination and on large-area devices further demonstrate the significant potential of EtNO as a CIL.