A Facile and Green Synthesis of Superparamagnetic Fe3O4@PANI Nanocomposite with a Core–Shell Structure to Increase of Triplet State Population and Efficiency of the Solar Cells

Abstract The superparamagnetic nanocomposite of Fe3O4@PANI by using solid-state (solvent-free) in-situ polymerization method is synthesized, characterized, and designed for application in polymer solar cells (PSCs). The structural, optical, electrochemical, morphological, and photovoltaic properties of Fe3O4@PANI are investigated. The results indicate that the Fe3O4@PANI with a core-shell structure is synthesized successfully. The magnetic properties of Fe3O4@PANI exhibit superparamagnetic property with a saturation magnetization of 44.09 emu/g. Cyclic voltammetry measurements are conducted to ascertain the position of both the HOMO (-5.26 eV) and LUMO (-3.65 eV) levels, and the chemical band gap is found in the range 1.61 eV. The maximum power conversion efficiency (PCE) of the PSCs based on FTO│TiO2│PANI@Fe3O4│Al system reaches 1.53% with an open circuit voltage (Voc) of 0.46 V, a short circuit current density (Jsc) of 4.24 mA/cm2, and a fill factor (FF) of 0.47 under AM 1.5 G (60 mW/cm2) illumination. In the following, the role of superparamagnetic nanoparticles of Fe3O4 in increasing solar cell efficiency is studied. In this structure, the magnetic field of Fe3O4 increases the population of triplet state in PANI and subsequently cell efficiency. Both active layer synthesis and cell construction are green, simple, cheap, stable, and have relatively high yields. It is concluded that such cells offer a promising new approach to commerce the new solid-state polymer solar cells.