Incorporating Naphthalene and Halogen into Near-Infrared Double-Cable Conjugated Polymers for Single-Component Organic Solar Cells with Low-Voltage Losses.

The invention of near-infrared pedant-based double-cable conjugated polymers has demonstrated remarkable efficacy in single-component organic solar cells (SCOSCs). This work focuses on the innovative double-cable conjugated polymers aimed at attaining good absorption and suitable energy levels. Specifically, in the aromatic side units, the electron-donating (D) part is designed using a thieno[3,4- c ]pyrrole-4,6-dione (TPD) as a core unit, flanked by two cyclopentadithiophene groups on either side. The electron-deficient (A) terminal groups consist of 2-(3-oxo-2,3-dihydro-1 H -cyclopenta[ b ]naphthalen-1-ylidene) malononitrile (NC), which can be further modified through fluorination to modulate the physical properties and packing modes of the acceptor material. The resulting double-cable conjugated polymers exhibit broad absorption spectra spanning 500-850 nm and possess lowered Frontier energy levels when incorporating fluorine elements, providing decreased voltage losses in SCOSCs. Therefore, SCOSCs fabricated using these polymers have demonstrated power conversion efficiencies ranging from 7.6 to 10.2%, in which fluorine-containing double-cable conjugated polymers showed higher PCEs due to more favorable crystalline packing, enhanced exciton dissociation probability, and charge-transporting ability.