Computational Screening of Chiral Organic Semiconductors: Exploring Side-Group Functionalization and Assembly to Optimize Charge Transport

Abstract

Molecular materials are challenging to design as their packing arrangements, and hence their properties, are subject to subtle variations in the interplay of soft intermolecular interactions. Rational design of new molecular materials with tailored properties is currently hampered by the difficulty in predicting how a candidate molecule will pack in space and how to control the particular polymorph obtained experimentally. Here, we develop a rapid screening approach to aid the material design process, which is then applied to predict the charge-transfer properties of 1344 helicene compounds that have potential as organic electronic materials. Our approach bridges the gap between single-molecule design, molecular assembly, and the resulting charge-carrier mobilities. We find that fluorination significantly improves electron transport in the molecular material by over 200%, while side groups containing triple bonds largely lead to improved transfer integrals. We validate our screening approach through the use of full crystal structure prediction for the most promising compounds to confirm the presence of favorable packing motifs that maximize charge mobility.