Recent Progress in Photonic Design and Charge Transport Optimization for Organic Solar Cells

ABSTRACT: Organic solar cells (OSCs) are attracting attention as a possible replacement for traditional photovoltaics because they are low-cost, lightweight, and have adjustable optoelectronic features. The commercialization of single-junction OSCs still faces challenges in achieving high power conversion efficiency (PCE) and operating stability. Recent developments in photonic crystals, plasmonics, nanophotonics, and metamaterials have significantly addressed these issues, especially in single-junction systems. This paper reviews the latest advancements in charge transport engineering, nanophotonic light-trapping methods, and nanostructured interfaces specifically designed for single-junction OSCs. It also highlights recent record-breaking efficiencies that exceed 20% PCE. We discussed integrating plasmonic nanoparticles, optical microcavities, nanostructured electrodes, and improved photonic materials to increase light absorption, exciton dissociation, and charge collection within the specific limitations of single-junction devices. Furthermore, we stress the important role of computational modeling and recent experimental breakthroughs in enhancing optical and electrical performance. Rather than treating optical and electrical processes independently, this review emphasizes the synergistic role of photonic enhancement strategies in simultaneously improving light trapping and charge transport, highlighting how nanophotonic designs influence carrier generation, recombination, and extraction in single-junction OSCs.