Effect of charge transport channel and interaction of IDT type dyes on photoelectric characteristics

Abstract In this work, four indacenodithiophene (IDT) dyes (L348-L351), with the same brominated triphenyl amine donor and phenylcarboxylic acid unit acceptor as well as different auxiliary acceptors, have been investigated. The photoelectric properties of molecules were analyzed by density functional theory (DFT), including electronic structure, absorption spectra, intramolecular charge transfer (ICT), dye activity and photoelectric parameters (JSC and VOC). ICT is mainly evaluated by parameters such as charge density difference (CDD), DCT, Δr, Sr, Δq and coulomb attraction (EC). The photoelectric parameters are mainly evaluated by factors, such as excitation lifetime (t), electron injection lifetime (τ), adsorption energy (Eads), vertical dipole moment (μnormal) and the internal reorganization rate calculated by the Marcus theory. The calculation results show that molecule L350 (introducing benzothiadiazole group) has good charge separation and excellent electron transfer ability. It is hoped that the theoretical simulation can be used to improve the efficiency of screening and optimizing dyes, which provides a reference for improving the performance of photovoltaic materials.