Exploring Organic Small-Molecule Solar Cells: From Fundamental Principles to Advanced Device Architectures

Organic small-molecule solar cells (OSCs) have gained attention as strong contenders for next-generation photovoltaics, thanks to their distinct advantages like adjustable energy levels, flexible molecular design, and the potential for low-cost production. This paper reviews the crucial elements of OSC technology, with an emphasis on its operational mechanisms, material innovations, device architectures, and the latest advancements in research. The working principles, including exciton generation, charge separation, and collection mechanisms, are discussed in detail. Furthermore, the review explores the donor-acceptor materials, with an emphasis on how molecular engineering has optimized the efficiency and stability of OSCs. The comparison between single-layer and bilayer device structures is analyzed, highlighting their respective advantages and limitations in terms of efficiency, stability, and recombination losses. Finally, the latest breakthroughs in OSCs are presented, underscoring the significant progress in power conversion efficiencies and long-term operational stability. This paper seeks to offer an in-depth analysis of the current advancements and future potential of small-molecule organic solar cells.