Optoelectronic Properties of Tetracyanoquinodimethane (TCNQ) Related Compounds for Applications to OSCs and OLEDs: A Theoretical Study

Tetracyanoquinodimethane (TCNQ) and related compounds are thoroughly investigated as potential innovative organic semiconductors and singlet fission (SF) materials. The TDDFT method with the PBE0/Def2-TZVP level is used to determine the geometrical structures, atomic dipole corrected Hirshfeld (ADCH) charge, population, dipole moment (μ), band gaps, different density of states (DOSs), excitation energies, hole-(λH) and electron-(λE) reorganization energies, SF properties, absorption-emission spectra, transition density matrix (TDM), electron localization function (ELF) of these molecules, and open circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE) of possible optoelectronic devices. At the CAM-B3LYP/6-311G** level, we examine the ground and excited state characteristics of 44 modeled TCNQ-related molecules. Two fundamental criteria, namely, the SF driving force (Δ = E(S1) – E(T1)) and the triplet–triplet annihilation (TTA) probability (Ω = E(S1) – 2E(T1)), have been analyzed to demonstrate the SF properties of these model materials. The current study reveals effective hole transport materials (HTMs) and electron transport materials (ETMs) in organic light-emitting diodes (OLEDs), and suitable SF materials in organic solar cells (OSCs) were chosen considering those multiple factors.