Flashing-ratchet effect on directional photocurrent in organic devices

The organic flashing-ratchet experiment demonstrates that current can be measured even in the absence of a net bias. Motivated by these experiments, we employ the Marcus theory to simulate the charge-hopping process under a time-varying, nonuniform electric field without a net driving force. Our findings indicate that directional motion is observed only when both temporal and spatial conditions are satisfied simultaneously, namely time-dependent flashing and spatial asymmetry in the ratchet potential. The ratchet current can be optimized by selecting a specific flashing frequency and spatial structure. In addition, we discuss both the temperature effect and the anisotropic effect of the flashing ratchet, allowing the current of an actual device to be predicted. The presence of a time-varying and spatially nonuniform electric field in organic photoelectric devices suggests that the flashing-ratchet effect is an intrinsic property of these devices. Based on this, our research opens up a robust routine for designing the intrinsic electric field to enhance the performance of optoelectronic devices.