Fused ring pyrrolo[3,2-b]pyrrole-based tilde-shaped acceptor molecules for highly efficient organic solar cells

Abstract

Tilde-shaped materials based on pyrrolo [3,2-b]pyrrole (PP) have attracted a lot of interest as potential acceptors for organic solar cells (OSCs) because of their wide range of energy levels, high absorption efficiency, and three-dimensional (3D) charge transport properties. Herein, we have effectively developed and characterized tilde-shaped PPIC-based acceptor materials (RK1-RK7) using PP as the central-core unit to probe their optical and optoelectronic characteristics. These engineered tilde-shaped (RK1-RK7) materials displayed deeper HOMO levels and more significant extinction coefficients, likely to provide improved phase separation morphology while blend formation. The complete theoretical characterization of these molecules (RK1-RK7) and reference (R) has been achieved using advanced quantum chemical approaches. In addition, density functional theory (DFT) and time-dependent (TD-DFT) simulations have explored the photophysical and optoelectronic properties. Optical properties, frontier molecular orbital (FMO), light harvesting efficiency (LHE), the density of states (DOS), open-circuit voltages, reorganization energy of holes and electrons, and transition density matrix (TDM) have all been studied in these substances. RK4 has an absorption maximum (λmax) at 783.47 nm and an optical band gap minimum of 0.87 eV. The mechanism of extraordinary charge shifting at the donor-acceptor interface was also revealed by a detailed investigation of RK4/PTB7-Th. Our proposed approach is the key backbone to construct efficient molecules for OSCs.