Effect of synthetic accessibility on the commercial viability of organic photovoltaics

Abstract

For organic photovoltaics (OPVs) to become a viable source of renewable energy, the synthesis of organic active-layer materials will need to be scaled to thousands of kilograms. Additionally, the ultimate cost of these materials will need to be low enough to constitute only a small fraction of the cost of the solar cell module. In this study, we present a quantitative analysis, based on published small-scale synthetic procedures, to estimate the materials costs for several promising OPV materials when produced in large quantities. The cost in dollars-per-gram ($ per g) is found to increase linearly with the number of synthetic steps required to produce each organic photoactive compound. We estimate the cost-per-Watt ($ per W_p) as a function of power conversion efficiency (PCE) for an archetypal OPV structure and find that a relatively simple molecule requiring only 3 synthetic steps will contribute a cost of 0.001 to 0.01 $ per W_p, given a solar module PCE of 10%. In contrast, a relatively complicated molecule requiring 14 synthetic steps will contribute costs in the range of 0.075 to 0.48 $ per W_p. Our findings suggest that the commercial viability of an OPV technology may depend on the synthetic accessibility of its constituent active layer materials. Additionally, this work stresses the importance of optimizing synthetic routes to minimize solvent and reagent usage as well as to minimize the number of required workup procedures in the scaled production of OPV materials.