Theoretical design and characterization of new terpolymer donors based on PTB7Ir for high-efficiency triplet-material-based organic photovoltaics.

ABSTRACT

In the current work, eleven terpolymer donors with different electron-withdrawing groups were designed and investigated based on the reported PTB7Ir to screen outstanding donors for triplet-material-based organic photovoltaics (T-OPVs). Geometry structures, frontier molecular orbital energy levels, energy driving forces (ΔE L-L), absorption spectra, energy differences between S1 and T1 states (ΔE ST), and driving forces of the triplet charge recombination (-ΔG CRT) of PTB7Ir and designed 1-11 systems were evaluated by DFT and TD-DFT methods to estimate the light absorption abilities and the charge transfer dynamics. The results show that designed 5, 8, 10 and 11 possess larger spin-orbit couplings (SOC) affinity and smaller ΔE ST and -ΔG CRT values, which could effectively suppress the triplet charge recombination process at the donor/acceptor interface. Excitingly, the designed terpolymer 10 presents enhanced light absorption, revealing that it will be a promising donor candidate for high-performance T-OPV devices. Moreover, the results can provide theoretical guidelines to predict new terpolymer donors of T-OPVs.