External electric field-dependent photoinduced charge transfer in non-fullerene organic solar cells

Based on Marcus theory, the photoinduced electron transfer properties of D-A type non-fullerene acceptor organic solar cells (OSCs) under the dependence of external electric field (F-ext) were investigated. The research results shown that the charge transfer mode under different F-ext intensities changes with certain regularity. Focusing on the important parameters (delta G, lambda, and V-DA) that affect the charge transfer rate, it was found that both charge separation (|delta G(CS)|>lambda (1.3019 vs 0.8275 eV at F-ext = 0) and charge recombiation (|delta G(CR)|>lambda, (1.9633 vs 0.8275 eV)) processes occur in the Marcus inverted region. The delta G(CS) is relatively sensitive to F-ext, and the calculated delta G(CS) at different F-ext intensities yields an increment of 0.0073 eV, which is also the main reason for the increase in the rate of charge separation. The delta G(CR) ranges between-1.9633 and-1.9637 eV, is insensitive to F-ext, and delta G(CR) is significantly smaller than delta G(CS), which makes the charge recombination rate significantly smaller than the charge separation rate. For V-DA, it is found that V-DA will transition to a new level only when the F-ext intensity reaches a certain intensity, which also enables to obtain a faster charge separation rate. By studying the charge transfer parameters in different polar solvents, it is found that polar solvents can indeed increase the charge transfer rate. To a certain extent, our results also demonstrate that the addition of F-ext can further improve the performance of non-fullerene acceptor OSCs.

Automated summary

Based on Marcus theory, the photoinduced electron transfer properties of D-A type non-fullerene acceptor organic solar cells (OSCs) under the dependence of external electric field (F-ext) were investigated. The research found that the charge transfer mode changes with the intensity of external electric field and the important parameters (delta G, lambda, and V-DA) play a crucial role in the charge transfer rate.