Temperature Dependence of the Luminescence Spectra of a 5CB Liquid Crystal and its Phase Transitions

The spectroluminescence properties of 4cyano4'pentylbiphenyl CH 3 (CH 2 ) 4 (C 6 H 4 ) 2 CN (5CB) were studied in the temperature range 4.2–297 K. A red shift of the fluorescence spectrum was noted with increasing temperature. The long-wavelength shifts in these spectra were also analyzed. Comparison of the temperature dependence curves for the emission at the band maxima λ max and their halfwidths Δλ/2 in the fluorescence spectra and the results of a differential scanning calorimetry (DSC) study showed that phase transitions occur in the 5CB liquid crystals at ~230 and ~260 K.