Photochemical Doping of an Adaptive Mix-Conducting p−n Junction

Existing photovoltaic junctions typically contain only electronic charge carriers, and they rely on the built-in electronic asymmetry between constituent materials to separate photogenerated electrons and holes. In this Letter, we report the observation of a photovoltaic response and photochemically induced near-infrared absorption from a mixed ionic−electronic junction constructed from two intrinsic polyacetylene ionomers with oppositely charged mobile counterions. We propose that the asymmetry in ionic charge carriers across the junction leads to the separation of photogenerated carriers and the in situ photochemical doping of both ionomers under illumination. Unlike purely electronic junctions, the doping level of mixed ionic−electronic junctions can change adaptively with light intensity due to the interaction between ionic and electronic carriers. The unique working mechanism of mix-conducting junctions could be used for designing solar cells and adaptive photoelectronic devices.