Influência de nanopartículas metálicas e pequenas moléculas no desempenho de células solares orgânicas

Abstract

The search for clean and renewable energy sources places photovoltaic technology among the key solutions for the future global energy landscape. Among emerging alternatives, Organic Solar Cells (OSCs) stand out due to their lightweight nature, mechanical flexibility, and the prospect of low-cost fabrication. The most significant recent advances have been achieved using bulk heterojunction (BHJ) architectures based on the modern class of non-fullerene acceptors (NFAs). In this context, the Y6 molecule blended with the donor polymer PM6 (PM6:Y6) constitutes one of the most efficient and widely studied systems to date. Nevertheless, a major challenge for commercial deployment remains the mitigation of efficiency losses arising from the competition between charge extraction and charge recombination within the device. The aim of this work is to investigate the influence of metallic nanoparticles and small molecules on the performance of organic solar cells, with the goal of improving photovoltaic parameters through interfacial engineering of BHJ-OSC multilayer structures. Different hole transport layers (HTLs) were evaluated, namely the polymeric PEDOT:PSS and the small molecule Br-2PACz, each combined with interlayers of 𝐴𝑢 or 𝑀𝑜𝑂3 nanoparticles synthesized via the pulsed laser ablation in liquid (PLAL) method. Steady-state characterization based on current density–voltage 𝐽–𝑉 measurements demonstrated that the Br-2PACz/Au nanoparticle configuration provides the most effective combination, yielding superior photovoltaic parameters compared to devices employing PEDOT:PSS as the HTL. Charge carrier dynamics in the optimized Br-2PACz/Au nanoparticle system were further investigated through a correlated analysis of transient photocurrent (TPC), transient photovoltage (TPV), and photo-CELIV measurements. Supported by an analytical photocurrent model, the results indicate that the incorporation of nanoparticles enhances charge carrier mobility. This analysis confirms that interfacial optimization is critical, as the combined action of Au nanoparticles and Br-2PACz reduces the imbalance between recombination and hole extraction losses. This effect is evidenced by a significant reduction in the parameter 𝜃0, a figure of merit directly correlated with improvements in fill factor (FF) and power conversion efficiency (PCE). Overall, the results demonstrate that charge extraction and recombination dynamics play a central role in photovoltaic device optimization and validate the multilayer interfacial engineering approach as an effective strategy to enhance charge transport and maximize the efficiency of organic solar cells.