  Polymer based organic photovoltaic (OPV) technology offers a relatively
inexpensive option for solar energy conversion provided its efficiency
increases beyond the current level (6-7%) along with significant improvements
in operational lifetime. The critical aspect of such solar cells is the complex
morphology of distributed bulk heterojunctions, which plays the central role in
the conversion of photo-generated excitons to electron-hole pairs. However, the
fabrication conditions that can produce the optimal morphology are still
unknown due to the lack of quantitative understanding of the effects of process
variables on the cell morphology. In this article, we develop a unique
process-device co-simulation framework based on phase-field model for phase
separation coupled with self-consistent drift-diffusion transport to
quantitatively explore the effects of the process conditions (e.g., annealing
temperature, mixing ratio, anneal duration) on the organic solar cell
performance. Our results explain experimentally observed trends of open circuit
voltage and short circuit current that would otherwise be deemed anomalous from
the perspective of conventional solar cells. In addition to providing an
optimization framework for OPV technology, our morphology-aware modeling
approach is ideally suited for a wide class of problems involving porous
materials, block co-polymers, polymer colloids, OLED devices etc.
