Molecular Design of Highly Efficient Organic Solar Cells Based on Nonfullerene Acceptors
Abstract
Abstract: The University of Arizona proposes a four-year multi-scale computational research project, to be carried out in strong collaboration with experimental groups within the ONR Polymer Program, in order to understand how chemical structure, molecular-scale packing, and the global morphology impact the electronic and optical processes taking place during device operation in nonfullerene based organic photovoltaic (OPV) devices.Our multi-pronged efforts aim at: (i) Establishing relationships among molecular structures, molecular packings, absorption and emission characteristics, electronic structures of the CT states, and voltage losses. (ii) Developing reliable computational procedures: to evaluate the Flory-Huggins ~ parameters as a function of temperature for donor/acceptor blends; to determine the range of optimal ~(T) values; to build the phase diagram of donor/acceptor blends; and to provide guidance for the molecular engineering of ~(T). (iii) Developing efficient Machine Learning models using morphology-based descriptors that are obtained from all-atom and coarse-grained molecular dynamics simulations as well as experimental data.Specifically, we will:1. Extend our original three-state model for absorption to describe the characteristics of the charge transfer (CT) state emissions in donor-acceptor (D/A) blends and quantitatively assess the impact of the hybridization between the CT and local-exciton (LE) states on the luminescence efficiencies of the D/A active layers and the non-radiative voltage losses. This work will be performed in close collaboration with the groups of David Ginger and Alex Jen at the University of Washington.2. (a) Understand the role of molecular packing on the electronic-structure properties of D/A interfacial CT states and non-radiative voltage losses in high-efficiency nonfullerene-based active layers, such as the PBDB-T-2F/BC-4F blend that currently holds the PCE efficiency record of over 16%. (b) Address the elements of the ~global~ morphology associated with domain size, purity, and degree of crystallinity, by combining all-atom and coarse-grained molecular dynamics simulations. This aspect will be pursued in collaboration with the Ade group.3. Use the results of these all-atom and coarse-grained molecular dynamics simulations in conjunction with a broad set of experimental data, in particular coming from the Ade group, to build a morphology and property database that will be used to train machine-learning models.The results will aid in the design of materials for more efficient organic solar cells, pushing OPV closer to the Shockley-Queisser limit, which offers the opportunity for light-weight, flexible, and shock-resistant mobile power generation during Navy and Marine Corps operations.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 11, 2020
- Source ID
- N000142012110
Entities
People
- Jean-Luc Brédas
Organizations
- Office of Naval Research
- United States Navy
- University of Arizona