Multilayered organic semiconductors for high performance optoelectronic stimulation of cells

The efficiency of devices for bioelectronic applications, including cell and tissue stimulation, is heavily dependent on the scale and the performance level. With miniaturization of stimulation electrodes, achieving a sufficiently high current pulse to elicit action potentials becomes an issue. Herein we report on our approach of vertically stacking organic p-n junctions to create highly-efficient multilayered organic semiconductor (MOS) photostimulation device. A tandem arrangement substantially increases the photovoltage and charge density without sacrificing lateral area, while not exceeding 200–500 nm of thickness. These devices generate 4 times higher voltages and at least double the charge densities over single p-n junction devices, which allow using lower light intensities for stimulation. MOS devices show an outstanding stability in the electrolyte that is extremely important for forthcoming in vivo experiments. Finally, we have validated MOS devices performance by photostimulating fibroblasts and neuroblasts, and found that using tandem devices leads to more effective action potential generation. As a result, we obtained up to 4 times enhanced effect in cell growth density using 3 p-n layered devices. These results corroborate the conclusion that MOS technology not only can achieve parity with state-of-the-art silicon devices, but also can exceed them in miniaturization and performance for biomedical applications.