From Molecules to Materials: Molecular and Crystal Engineering Design of Organic Optoelectronic Functional Materials for High Carrier Mobility

Abstract

The reorganization energy and the charge transfer integral between the initial and final states are two key parameters of charge transport. In this study, we find that the internal reorganization energies of molecules can be reduced effectively by cyanation on the tetracene molecule, which is helpful to improve the carrier mobilities of investigated molecules. On the basis of the polymorph predictor, the appreciated crystal structures of 5-cyanotetracene (1CT), 5,11-dicyanotetracene (2CT), and 5,6,11,12-tetracyanotetracene (4CT) with π–π stacking favorable to enhance the charge transfer integral were obtained. Benefiting from a low internal reorganization energy and dense packing structure, high hole motilities (6.0 and 6.2 cm2 V–1 s–1 for 1CT-9 and 4CT-2, respectively) were achieved. Both 1CT-9 and 4CT-2 are promising candidates for high carrier mobility organic optoelectronic functional materials. The process that constructs crystal structures from single molecules provides a rational way for the search of high-performance organic photovoltaic materials.