Printable MoO_x Anode Interlayers for Organic Solar Cells

Abstract Currently, solution‐processed MoO_x 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 MoO_x (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.