Plasmonic Mn@Cu Nanostructures Boost Efficiency and Stability in PCPDTBT : PC 71 BM Solar Cells

ABSTRACT In this study, manganese‐copper (Mn@Cu) plasmonic nanostructures (NSs) were synthesized using a simple chemical reduction method and integrated into inverted thin‐film organic solar cells (TFOSCs) to improve light absorption through localized surface plasmon resonance (LSPR). The Mn@Cu NSs were embedded in a PCPDTBT:PC 71 BM bulk heterojunction (BHJ) active layer. Optical and morphological analyses confirmed the formation of well‐defined core‐shell NSs with broadband absorption and increased light scattering. Devices with 2 wt% Mn@Cu NSs achieved a power conversion efficiency (PCE) of 4.58%, achieving a two‐fold increase over the efficiency of the pristine (2.28%). This enhancement is attributed to improved exciton generation, higher charge carrier mobility, and reduced recombination losses, as shown by external quantum efficiency (EQE) and electrical impedance spectroscopy (EIS) measurements. Furthermore, the Mn@Cu‐doped devices demonstrated excellent operational stability over time under ambient, unencapsulated conditions. These results confirm the potential of Mn@Cu NSs as effective plasmonic additives for improving both the efficiency and stability of organic photovoltaic devices.