Synthesis and photovoltaic applications of schiff-base benzothiadiazole-based d-a-d organic molecule

Organic optoelectronic materials have important and effective roles, and applications in today's increasingly technological World. Researches in optoelectronics focus on the development of devices based on next-generation semiconducting material systems that will meet the eco-friendly energy requirements in developing technologies. Organic molecules characterised by low cost, flexibility, easy functionalisation and processability, and applicability on different surfaces have displayed successful applications in a wide range of optoelectronic devices such as organic solar cells (OSCs) organic light emitting diodes (OLEDs), organic field effect transistors (OFETs), lasers, and other photovoltaics (PVs). Organic semiconducting molecules have been of increasing interest in recent years compared to related conjugated polymers due to well-characterised molecular structures, low cost, simplicity in synthetic strategies and purification methods, better processability and reproducibility. A little modification in the structure of organic molecules significantly alters and affects the electrochemical and optical properties of the molecules. In addition, these molecules provide excellent device performance using a vapour deposition technique owing to their high solubility. Conjugated organic molecules possessing donor (D) and acceptor (A) units are one of the most effective methods for designing materials in various optoelectronic applications. Benzothiadiazole (BT) is a strong acceptor due to its high electron affinity and commonly used for the design of molecular systems with low HOMO−LUMO gap. Thieno[3,2-b]thiophene (TT) derivatives are extensively used as donor compounds in material chemistry. Thiophene ring has advantages in D−A containing molecules due to its electron-rich, easy modifications, high chemical and thermal stability. Attachment of electron-rich groups, such as triphenylamine (TPA) and dimethoxytriphenylamine (OMeTPA) on both ends of the molecules further altered their optical and electrochemical properties. Schiff bases have long been synthesised and applied in a wide variety of biological and chemical applications. In recent years, straightforwardness in their syntheses and ability to modify them have been increasing; particularly in optoelectronic applications. For next-generation material synthesis, Schiff base will be used as a conjugated bridge between acceptor and TT substituted by donor groups. In this study, we exploited the donating character of TT and the withdrawing character of BT to create DA and DAD molecular systems. Although results obtained in this research are inconclusive, the potential obtainable diversity in this work is wide; and there remains great room for improvement upon what has been obtained.