A Solution-Processed MoOx Anode Interlayer for Use within Organic Photovoltaic Devices

A simple, solution‐processed route to the development of MoOx thin‐films using oxomolybdate precursors is presented. The chemical, structural, and electronic properties of these species are characterized in detail, within solution and thin‐films, using electrospray ionization mass spectrometry, grazing angle Fourier transform infrared spectroscopy, thermogravimetric analysis, atomic force microscopy, X‐ray photoelectron spectroscopy, and ultraviolet photoelectron spectroscopy. These analyses show that under suitable deposition conditions the resulting solution processed MoOx thin‐films possess the appropriate morphological and electronic properties to be suitable for use in organic electronics. This is exemplified through the fabrication of poly(3‐hexylthiophene):[6,6]‐phenyl C61 butyric acid methyl ester (P3HT:PC61BM) bulk heterojunction (BHJ) solar cells and comparisons to the traditionally used poly(3,4‐ethyldioxythiophene)/poly(styrenesulfonate) anode modifying layer. A solution‐processed method to deposit MoOx layers using oxomolybdate precursors is developed. The chemical, morphological, and electrical properties of these films are found to be suitable for use as anode modifying layers in bulk‐heterojunction solar cell devices. To achieve high performance in such devices, the density of Mo5+ sub‐gap states within the MoOx has to be controlled.