Printable MoOx Anode Interlayers for Organic Solar Cells.

Abstract

Currently, solution-processed MoOx anode interfacial layers (AILs) can only be fabricated by the spin-coating method in organic solar cells (OSCs), which severely limits their use in practical productions where large-area printing techniques are used. Herein, a facile method is demonstrated to prepare highly conductive MoOx (denoted EG:Mo) that can be processed by printing methods such as wire-bar and blade coatings. The EG:Mo films are prepared by depositing an aqueous solution containing ammonium heptamolybdate (VI) tetrahydrate (NMo) and ethylene glycol (EG) and annealing at 200 °C. UV-vis absorption and X-ray photoelectron spectroscopy measurements confirm that Mo (VI) can be reduced to Mo (V) by EG, resulting in the n-doped EG:Mo. Using the EG:Mo as AILs, an OSC based on a PB3T:IT-M active layer exhibits a power conversion efficiency (PCE) of 12.1%, which is comparable to that of the PEDOT:PSS modified devices. More importantly, EG:Mo AILs can be processed by wire-bar and blade-coating methods, and the corresponding devices show PCEs of 11.9% and 11.5%, respectively. Furthermore, the EG:Mo AIL is processed by wire-bar coating to fabricate a large area device (1.0 cm2 ), and a PCE of 10.1% is achieved.