Exploring the Electronic, Optical, and Charge Transfer Properties of A-D-A-Type IDTV-ThIC-Based Molecules To Enhance Photovoltaic Performance of Organic Solar Cells

Abstract

Improving the charge mobility and optoelectronic properties of indacenodithiophene<b>-</b>based small molecule acceptors is a key challenge to improving overall efficiency. In this current research, seven newly designed molecules (<b>DT1-DT7</b>) comprising the indacenodithiophene<b>-</b>based core are presented to tune energy levels, enhance charge mobility, and improve the photovoltaic performance of <b>IDTV-ThIC</b> molecules via density functional theory. All the molecules were designed by end-capped modification by substituting terminal acceptors of <b>IDTV-ThIC</b> with strong electron-withdrawing moieties. Among all the examined structures, <b>DT1</b> has proved itself a superior molecule in multiple aspects, including higher λ_max in chloroform (787 nm) and gaseous phase (727 nm), narrow band gap (2.16 eV), higher electron affinity (3.31 eV), least excitation energy (1.57 eV), and improved charge mobility due to low reorganization energy and higher excited state lifetime (2.37 ns) when compared to the reference (IDTV-ThIC) and other molecules. DT5 also showed remarkable improvement in different parameters, such as the lowest exciton binding energy (0.41 eV), leading to easier charge moveability. The improved open-circuit voltage of <b>DT4</b> and <b>DT5</b> makes them proficient molecules exhibiting the charge transfer phenomenon. The enlightened outcomes of these molecules can pave a new route to develop efficient organic solar cell devices using these molecules, especially <b>DT1</b>, <b>DT4</b>, and <b>DT5</b>.