Fig. 1

Crystal structure and orientation in the ab-plane of tetracene. a Crystal structure, hydrogen atoms not shown. Red (horizontal) axis is a, green axis is b. Two molecules, m and n, make up the unit cell. b Polarized photoluminescence measured at 531 nm using 514-nm excitation of the sample used for transistor (b) and transmission electron microscopy (c) measurements. Data are rotated so that the a axis/[100] direction aligns with 0°