This study explores how plasmonic nanoparticles affect absorption, transmission, and reflection—three important performance metrics in organic-inorganic halide perovskite solar cells (PSCs). Through an investigation of different types of nanoparticles and their concentration in the composite layer, the study provides important information for improving PSC design in order to increase overall efficiency. The results highlight the importance of the type and volume fraction of nanoparticles in the composite layer, which influence the spectral characteristics of the solar cell, such as absorption, reflection, and transmission. These findings could encourage PSCs to be widely used as a practical and affordable renewable energy source, which would advance the development of affordable and efficient solar energy technologies.