An overview of HPDLC films and their applications

The fusion of holography to the LC-polymer composites give rise to holographic polymer dispersed liquid crystal (HPDLC) technology. The concentration of monomer unit in HPDLC films is quite high as compared to the other polymer-LC composite films. Difference in the rate of polymerisation in different regions of composite film gives rise to alternate bright and dark fringes. In this review article along with the underlying principle of HPDLC films, we have discussed some electro-optical (EO) parameters like response time, diffraction efficiency (DE) and driving voltages necessary for the evaluation of a film. The classification and types of HPDLC gratings, which actually depend upon writing set up, grating period and thickness, has also found good space in this article. Recent advances to improve the efficiency of HPDLC films by varying material mixture and fabrication techniques is also discussed. Different types of evolved morphologies typically, LC droplet, Policryps and Polymer Scaffolding is described. Some trending applications of HPDLC films such as sensor, photonic crystals, mirrorless lasing etc are also highlighted.