4,7-di-(2-thienyl)-2,1,3-benzothiadiazole DTBT as active core for synthesizing small molecules to optoelectronic applications: A review

Small molecule (SM) organic semiconductor materials have attracted further attention for their significant advancement in light-harvesting devices and optoelectronic applications. Their ease of preparation, well-defined structures, cost-effectiveness, and highly tunable properties promote them for organic solar cells (OSCs), organic field-effect transistors (OFETs), and dye-sensitized solar cells (DSSCs) devices. Conjugated heterostructure donor pi-acceptor SMs have possessed an efficient system for stimulating faster charge transfer and achieving high photon-to-electron conversion. Their structure can be readily modified to incorporate additional pi-extension, further elevating their performance in OSCs, DSSCs, and OFETs. Benzothiadiazole, a well-known electron-deficient heterostructure moiety, when flanked by thiophene, has been strongly involved in numerous photoelectronic molecular designs. In this comprehensive review, we will explore the interaction between design strategies, side-chain engineering, molecular structure characteristics, and device engineering, as well as the molecular morphology of 4,7-di-(2-thienyl)-2,1,3-benzothiadiazole (DTBT) based organic SMs on the power conversion efficiency and the charge mobilities in three particular optoelectronic devices: OSCs, DSSCs, and OFETs. The challenges should be resolved with recommendations for DTBT-based molecular architectures for better device performance.