Theoretical designing of 9,9'-dicarbazole-based dye via end-group modification for indoor DSSC applications

Abstract

Molecular modeling has garnered significant attention in the realm of organic solar cells (OSCs) because it holds the promise of producing more efficient OSCs with notably enhanced power conversion efficiency (PCE). In this quest, we have undertaken a strategic modification of the acceptor moieties within the recently synthesized metal-free dicarbazole-based organic dye Cz-2, resulting in five novel theoretical dyes, designated as PT1-PT5. Numerous simulations encompassed both the newly designed compounds and the reference (Cz-2) by using DFT and TD-DFT, a comprehensive characterization aimed at enhancing photovoltaic and optoelectronic properties. We probed into the analysis of ground state geometry, frontier molecular orbitals, transition density matrix, optical properties, density of state, binding energy, molecular electrostatic potential, reorganizational energy, open-circuit voltage, and fill factor. Our findings unveiled a common trend among all the theoretical dyes, a reduction in band gap (Eg), a notable red-shift in absorbance ranging from 434nm to 554nm, and lowered binding and excitation energy. The decreased reorganization energy i.e., λe and λh, spanning a range from 0.0040 to 0.0052 eV and 0.0043 to 0.0075 eV respectively, promised significantly enhanced charge mobility. Intriguingly, the binding energies of all the designed compounds consistently registered values lower than that of reference (R), with figures ranging from 0.55 to 0.64 eV, compared to the binding energy of R (0.67 eV). These dyes show significant potential for indoor photovoltaics as they can absorb light in the visible range for indoor renewable energy applications. Our comprehensive analyses suggest that PT1-PT5 are promising candidates with great potential for advancing the field of renewable energy.