A New Conformationally Symmetrical Calix[4]pyrrole Based Supramolecular System for Liquid Crystalline and Window Layer Solar Cell Applications

The newly symmetrical liquid crystalline compounds (CPB1-CPB4) based on calix[4]pyrrole as central rigid core are synthesized via esterification reaction. All the four functionalized compounds exhibit columnar hexagonal phase (Col(h)) over a higher mesophase temperature range and further stabilized mesophase upto room temperature. The thermal behavior and optical texture are identified by using differential scanning calorimetry (DSC), Polarizing optical microscopy (POM) while the molecular organization of compound in mesogenic state by X-ray diffraction technique. The molecular system based on calix[4]pyrrole core with symmetrical nature exhibited columnar type self-assembly at room temperature. All these four supramolecules with different side spacer show higher thermal stability. Based upon the optimization, compound CPB2 has been further tested to implicate as optical window layer in thin films solar cell devices. The calix[4]pyrrole functionalized supramolecular liquid crystalline compound based thin films showed suitable transmittance, optical energy band gap together with absorbance and extinction coefficient. The linear dependence of current on the voltage demonstrated Ohmic behavior of the CPB2 films. The surface morphology to the developed samples designated nearly uniform deposition of the CPB2 thin films together with grain growth. The findings warrant suitability of the films to implicate these as an eco-friendly optical window layer in thin films based solar cells.

Automated summary

The newly synthesized symmetrical liquid crystalline compounds based on calix[4]pyrrole exhibited columnar hexagonal phase over a higher temperature range. Additionally, CPB2 compound showed potential as an optical window layer in thin film solar cell devices, displaying suitable transmittance and energy band gap. The findings suggest the suitability of calix[4]pyrrole functionalized supramolecular liquid crystal compounds as eco-friendly materials in solar cell applications.