• Olson, Dana C.
• Meyer, Jens
• Hammond, Scott R.
• Widjonarko, N. Edwin
• Ndione, Paul F.
• Garcia, Andres
• Lloyd, Matthew T.
• Sigdel, Ajaya K.
• Miedaner, Alexander
• Ginley, David S.
• Berry, Joseph J.
• Kahn, Antoine

Abstract

We have utilized a commercially available metal-organic precursor to develop a new, low-temperature, solution-processed molybdenum oxide (MoO{sub x}) hole-collection layer (HCL) for organic photovoltaic (OPV) devices that is compatible with high-throughput roll-to-roll manufacturing. Thermogravimetric analysis indicates complete decomposition of the metal-organic precursor by 115 C in air. Acetonitrile solutions spin-cast in a N{sub 2} atmosphere and annealed in air yield continuous thin films of MoO{sub x}. Ultraviolet, inverse, and X-ray photoemission spectroscopies confirm the formation of MoO{sub x} and, along with Kelvin probe measurements, provide detailed information about the energetics of the MoO{sub x} thin films. Incorporation of these films into conventional architecture bulk heterojunction OPV devices with poly(3-hexylthiophene) and [6,6]-phenyl-C{sub 61} butyric acid methyl ester afford comparable power conversion efficiencies to those obtained with the industry-standard material for hole injection and collection: poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The MoO{sub x} HCL devices exhibit slightly reduced open circuit voltages and short circuit current densities with respect to the PEDOT:PSS HCL devices, likely due in part to charge recombination at Mo{sup 5+} gap states in the MoO{sub x} HCL, and demonstrate enhanced fill factors due to reduced series resistance in the MoO{sub x} HCL.

Topics

• impedance spectroscopy
• molybdenum
• thin film
• thermogravimetry
• ester
• decomposition