Optimizing Stability through Conformational Locking and Ring Fusion Modulation in Organic Semiconductors

Abstract

The newly synthesized fused tetrathienophenanthroline (TTP) acceptor molecule, achieved via one-pot super acid catalyzed intramolecular cyclization, offers a promising alternative to the conventional benzodithiophene-4,8-dione (BDD) moieties in high-performance photovoltaic materials. The S, N heteroacene type TTP core exhibits complete planarity and enhanced electron richness compared to the BDD core, paving the way for fine tuning the morphological, optoelectronic, and frontier molecular energy levels in donor-acceptor-type materials. Side-chain engineering resulted in a balanced electron-rich nature of the monomer and the enhanced solubility/processability of the resulting polymers. These molecular strategies in PTTP-BDT contribute to improved stability and morphology, crucial for organic electronic device applications. Incorporating PTTP-BDT and PBDB-T as donor molecules in organic photovoltaics resulted in-power conversion efficiency (PCE) of ~ 3% for PTTP-BDT and ~8% for PBDB-T. The compromise in PTTP-BDT based device efficiency was attributed to lower and unbalanced charge mobility