Naphthobisthiadiazole-based nonfullerene acceptors for organic solar cells: molecular design, structure–property relationships, and synthetic perspectives

The development of nonfullerene acceptors (NFAs) based on -conjugated molecules has driven recent advances in organic solar cells (OSCs), with electron-deficient units playing a key role in their molecular design. This review highlights naphthobisthiadiazole (NTz)-based NFAs and their structure–property relationships, focusing on how fluorination, substitution, and π-extension regulate electronic structures, optical properties, blend morphology, and photovoltaic performance. Particular attention is paid to NTz-based NFAs combined with poly(3-hexylthiophene) (P3HT), a practical donor polymer with favorable cost and processability. This combination has enabled green-light wavelength-selective OSCs (GLWS-OSCs) that selectively convert green light into electricity while transmitting blue and red light for plant photosynthesis, providing a promising approach to greenhouse agrivoltaics. Finally, the synthetic complexity of NTz-based materials and the potential of direct C–H functionalization as a concise and scalable synthetic strategy are discussed.