Polyaniline and its composites engineering: A class of multifunctional smart energy materials

Polymer material provides significant advantages over the conventional inorganic material-based electronics due to its attractive features including miniaturized dimension and feasible improvisations in physical properties through molecular design and chemical synthesis. In particular, conjugate polymers are of great interest because of their ability to control the energy gap and electronegativity through molecular design that has made possible the synthesis of conducting polymers with a range of ionization potentials and electron affinities. Polyaniline (PANI) is one of the most popular conjugated polymers that has been widely explored so far for its multifunctionality in diverse potential applications. This review is focusing on the recent advances of PANI for smart energy applications including supercapacitors, batteries, solar cells and nanogenerators and the development in its synthesis, design, and fabrication processes. A details investigation on the different types of chemical process has been discussed to fabricate PANI in nanostructures, film, and composites form. The paper includes several studies which are advantageous for understanding: the unique chemical and physical properties of this polymer; and the easily tunable electrical properties along with its redox behavior; and different processes to develop nanostructures, film, or bulk form of PANI that are useful to derive its applicability in smart objects or devices.