Solution-grown, macroscopic organic single crystals exhibiting three-dimensional anisotropic charge-transport properties

A millimeter-sized solution grown (SG) organic single crystals based on 4-hydroxycyanobenzene (4HCB), which exhibited 3D anisotropic electrical properties along the three crystallographic axes a, b (constituting the main crystal flat face), and c (the crystal thickness), measured over several different samples, was reported. FET devices were used to estimate the directional carrier mobilities in the dark at room temperature and atmosphere along the two main axes. The mobility was determined by means of space charge-limited current (SCLC) measurements along the crystal thickness, axis c. X-ray diffraction analyses on some of the as-prepared crystals were conducted to verify the crystalline structure of the SG 4HCB crystals. The re-determination of the unit cell confirmed that the contacts were exactly aligned to the crystallographic axes a and b, and that the electrical stress did not alter the crystal lattice.