Study of dynamics and relaxation optical response of nematic liquid crystals doped with CdSe/ZnS quantum dots

Abstract

This study is devoted to the dynamics of the electro-optical response and relaxation time of LC cells with a nematic liquid crystal doped with CdSe/ZnS semiconductor quantum dots (QDs) and homogeneously oriented by rubbed polyimide. The influence of the nanoparticle concentration as well as the parameters of the alternating electric field has been studied. Experimental dependence of the response and relaxation time on the concentration of QDs was obtained. The increase of concentration of QDs in the range of 0.5–1.5 mg/ml results in a reduction of the optical response time. The threshold voltage reduced twice with increasing QD concentration up to 1.5 mg/ml as compared with the pure LC. For the first time it was shown that applying of unipolar square wave electric field to the LC cell reduces the optical response time even twice regardless to the frequency of the alternating electric field compared to bipolar square wave voltage.

Keywords:

• nematic liquid crystal
• quantum dots
• electro-optical characteristics
• threshold
• response time
• relaxation
• unipolar meander