5,11-Di(thiophen-2-yl)Tetracene: A Novel Tetracene Derivative for Efficient Singlet Fission with Enhanced Physical and Chemical Stability in Thin Films

Singlet fission (SF), a unique photophysical process in organic semiconductors, enables the splitting of a singlet exciton into two triplet excitons, offering the potential to exceed the Shockley–Queisser limit in solar cells by efficiently utilizing high-energy photons. For seamless integration with silicon solar cells, materials with the lowest excited singlet and triplet energies near 2.2 and 1.1 eV, respectively, are crucial. Among various SF candidates, tetracene derivatives have garnered significant attention due to their ability to sensitize silicon layers and their distinct spectroscopic properties. However, their limited chemical stability and challenges in modulating chromophore stacking and electronic interactions hinder practical applications. In this study, 5,11-di(thiophen-2-yl)tetracene (2T-Tc) is synthesized as a novel approach to overcome these limitations. This tetracene derivative with staggered thienyl substituents exhibits markedly improved chemical durability and phase stability in thin films while maintaining favorable SF kinetics and high triplet pair yields. Unlike rubrene or other tetracene derivatives, 2T-Tc readily forms stable polycrystalline thin films with enhanced interchromophore interactions, owing to its intrinsically planar tetracene core. Notably, it eliminates the need for additional post-processing to optimize photophysical properties. These findings underscore the pivotal role of molecular design in advancing SF materials for practical optoelectronic applications.