Electronic-Structure Role of Cobalt Oxide Nanoparticles in P3HT-Based Composites: From Thin-Film Fabrication to...

The present work aims to obtain composites of two semiconductor materials, poly-(3-hexylthiophene) (P3HT) and cobalt oxide (Co₃O₄), by in situ synthesis using the Sugimoto method. Both materials serve as hole-transport layers (HTL) in photovoltaic devices. The objective is to understand the effect of Co₃O₄ nanoparticles on P3HT, particularly how they interact and potentially alter the polymer's electronic structure. Co₃O₄ nanoparticles were synthesized by chemical precipitation as a byproduct of thin-film formation. They were incorporated at different concentration weight ratios (P3HT/Co₃O₄:1/0.03, 1/0.05, and 1/0.08) into the P3HT/Co₃O₄ composite. Their influence on the optoelectronic properties was analyzed. P3HT/Co₃O₄ films were characterized by various techniques: morphological (SEM, TEM, and AFM) and optoelectronic (FTIR and photoluminescence). The objective of the resulting composite is to improve HTL performance in a solar cell. Additionally, a DFT+U computational study was performed to investigate the P3HT adsorption on the Co₃O₄(110) surface. Three configurations showed that Co-S bond formation and ligand-to-metal charge transfer are the primary interactions, with van der Waals forces contributing significantly to the adsorption energy. Overall, the effect of cobalt oxide on P3HT was investigated experimentally and theoretically, contributing to a deeper understanding of the interfacial electronic interactions in P3HT/Co₃O₄ systems beyond conventional structural and optoelectronic analyses.