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This content will become publicly available on November 8, 2018

Title: Simplified Models for Accelerated Structural Prediction of Conjugated Semiconducting Polymers

We perform molecular dynamics simulations of poly(benzodithiophene-thienopyrrolodione) (BDT-TPD) oligomers in order to evaluate the accuracy with which unoptimized molecular models can predict experimentally characterized morphologies. The predicted morphologies are characterized using simulated grazing-incidence X-ray scattering (GIXS) and compared to the experimental scattering patterns. We find that approximating the aromatic rings in BDT-TPD with rigid bodies, rather than combinations of bond, angle, and dihedral constraints, results in 14% lower computational cost and provides nearly equivalent structural predictions compared to the flexible model case. The predicted glass transition temperature of BDT-TPD (410 +/- 32 K) is found to be in agreement with experiments. Predicted morphologies demonstrate short-range structural order due to stacking of the chain backbones (p-p stacking around 3.9 A), and long-range spatial correlations due to the self-organization of backbone stacks into 'ribbons' (lamellar ordering around 20.9 A), representing the best-to-date computational predictions of structure of complex conjugated oligomers. We find that expensive simulated annealing schedules are not needed to predict experimental structures here, with instantaneous quenches providing nearly equivalent predictions at a fraction of the computational cost of annealing. We therefore suggest utilizing rigid bodies and fast cooling schedules for high-throughput screening studies of semiflexible polymers and oligomers to utilizemore » their significant computational benefits where appropriate.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [2] ;  [2] ;  [2] ;  [3] ; ORCiD logo [4] ;  [2] ; ORCiD logo [5]
  1. Boise State Univ., ID (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. National Renewable Energy Lab. (NREL), Golden, CO (United States); Macquarie Univ., NSW (Australia)
  4. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  5. National Renewable Energy Lab. (NREL), Golden, CO (United States); Boise State Univ., ID (United States)
Publication Date:
Report Number(s):
NREL/JA-5900-70618
Journal ID: ISSN 1932-7447; TRN: US1800300
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 47; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S), SunShot National Laboratory Multiyear Partnership (SuNLaMP)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; semiconducting polymers; electronics; molecular dynamics
OSTI Identifier:
1412100