Toward Full-Color Vision Restoration: Conjugated Polymers as Key Functional Materials in Artificial Retinal Prosthetics

Abstract

For the prosthetic retina, a device replacing dysfunctional cones and rods, with the ability to mimic the spectral response properties of these photoreceptors and provide electrical stimulation signals to activate residual visual pathways, can relay sufficient data to the brain for interpretation as color vision. Organic semiconductors including conjugated polymers with four different bandgaps providing wavelength-specific electrical responses are ideal candidates for potential full-color vision restoration. Here, conjugated polymer photocapacitor devices immersed in electrolyte are demonstrated to elicit a photovoltage measured by a Ag/AgCl electrode 100 microns from the device of ≈−40 mV for 15–39 µW mm−2 of incident light power density at three wavelengths: 405 nm for blue photoreceptor candidate material, 534 nm for green, 634 nm for red. Photoresponse is substantially improved by introducing polymer donor/acceptor molecules bulk heterojunctions. Devices with bulk heterojunction configurations achieved at least −70 mV for green candidates with the highest at −200 mV for red cone candidates. These findings highlight the potential for organic materials to bridge the gap toward natural vision restoration for retinal dystrophic conditions such as age-related macular degeneration, Stargardt disease, or retinitis pigmentosa and contribute to the ongoing advancements in visual prosthetic devices.