Anisotropic electrical and optical studies of organic biphenyl single crystal grown by modified Czochralski technique

Abstract

Czochralski growth technique was used to grow organic single crystal of biphenyl along < − 230 > direction. The problems of excessive evaporation due to high vapour pressure and low melting point in BP was overcome by suitable modifications in the CZ set up. The monoclinic symmetry with space group P2₁/c for the grown crystal was confirmed by powder as well as single crystal X-ray diffraction. Intermolecular interactions present in the grown single crystal were analysed by Hirshfeld surface and 2-dimensional fingerprint plot. The biphenyl crystal (size 8 × 5 × 1.8 mm³) showed a transparency of 39% along < − 113 > and 3% along < − 230 > directions with a lower cut off wavelength of 311 nm and 307 nm, respectively. Photoluminescence emission peaks were observed at 494 nm and 488 nm in the two directions. Appreciable change in the dielectric constant (~ 56–~ 114) was observed along these two directions at RT which were frequency independent. The functional groups and thermal behaviour of BP crystals were also reported. Mechanical behaviour was explained with the help of void study and indentation technique. The anisotropic electrical and optical behaviour of BP can be used to fabricate devices with tunable output.