Slot-die coating is one of the promising methods for fabricating large-area polymer solar cells (PSCs) due to its compatibility with roll-to-roll printing and one-dimensional direct patterning. In this study, we investigated correlations between conformal film morphology of intermixed poly(3-hexylthiophene) (P3HT) and fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulkheterojunction (BHJ) material and universal control factors such as shim length, substrate temperature, and coating speed. The observed correlation equation is better matched to the meniscus coating parameter equation rather than to the traditional high-viscosity extrusion slot-die coating parameter equation. Based on our findings regarding the governing factors of the thin film formation of bulkheterojunction materials, we demonstrated the development of uniform large-area polymer solar cells with power conversion efficiency (PCE) of 3.07% under Air Mass 1.5 condition and the possibility of high-throughput production. (C) 2013 Elsevier B.V. All rights reserved.