Oligomer-based organic photovoltaic devices are promising candidates for the future of renewable energy due to low material cost, ease of fabrication, tunable properties, and operational flexibility. Limited theoretical understanding of molecular structure-device property relationships is preventing these devices from reaching their full potential. Of particular importance, theoretical models are required to describe hole mobility, a crucial measure of device performance. This is because the description of hole mobility is dependent on bulk electron donor material morphology, which cannot be empirically related to molecular structure. Our work centers on unraveling the relationships between molecular structure, material morphology, and device performance in order to enable prediction of promising new materials. As the first part of this work, we are using existing software packages to develop an approach to solve the challenging problem of predicting low energy polymorphs, or crystal structures, of conjugated oligomers present in device thin films. Theoretical work and progress toward this goal are presented. In the procedure, first molecular structures are generated with electronic structure methods. Next, the molecules are packed into randomly generated unit cells. Strategies to separately address both the �search� and �rank� problems of crystal structure prediction have been benchmarked for conjugated oligomers commonly used in organic photovoltaics. Using experimental crystal structures as a reference, we are tuning a theoretical approach for accurate prediction. The assumptions made to make this problem computationally tractable will also be discussed.

Progress toward <i>de novo</i> prediction of morphology in oligomer-based thin-film bulk heterojunction organic photovoltaic devices

247th National Meeting (2014)

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Progress toward de novo prediction of morphology in oligomer-based thin-film bulk heterojunction organic photovoltaic devices