In this study, we analyzed organic semiconducting single crystals composed of benzothienobenzothiophene derivatives (2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene, C-8-BTBT) grown by nematicphase liquid crystal (LC) solvent. As a result, we clarified that the crystal b-axis direction of the C-8-BTBT single crystals was consistent with the LC alignment direction. By optical evaluation and simulation based on density functional theory, we found that the C-8-BTBT single crystals in LC solvent exhibited a novel molecular conformation having alkyl chains oriented toward the fa-axis. (C) 2018 Elsevier B.V. All rights reserved.