A hybrid organic–inorganic electrode for enhanced charge injection or collection in organic optoelectronic devices

Here we report a novel hybrid organic–inorganic anode for organic light-emitting diodes (LEDs) and photovoltaic (PV) cells. This hybrid anode structure is realized from a composite of poly(3,4-ethylene dioxythiophene) doped with polystyrenesulfonic acid (PEDOT:PSS) and indium tin oxide (ITO) nanoparticles. Owing to the phase separation, this anodic structure leads to a graded work function from patterned ITO to the photoactive polymer, which in turn reduces the barrier height for holes by ∼70%. The resulting devices based on this design show up to 67% reduction in turn-on voltage (for polymer LEDs) and up to 40% increase in short-circuit current and power conversion efficiency (for PV cells). Current–voltage characteristics, Fowler–Nordheim analysis, SEM imaging and energy band diagram analysis are employed to characterize the improved performance of our devices. The reported approach is expected to be immensely useful for the molecular design of next-generation efficient organic devices.