p–n Heterojunction on dye-sensitized ZnO nanorod arrays and macroporous polyaniline network

Abstract

Recently, there has been growing interest in the design of ZnO based p–n heterojunctions. Because of the low interception of photons and creation of excitons, we introduce a version of the heterojunction photodiode in which the traditional ZnO nanoparticle film is replaced by a dense array of aligned and crystalline ZnO nanorods. The macroporous polyaniline (PANi) network is applied to the cathode and features a high surface area. To better accelerate the production of excitons on ZnO nanorod surfaces under sunlight, N719 dye is added to intercept photons and create excitons that are rapidly split at the ZnO nanorod surface, the electrons are injected into the ZnO nanorod and transferred to the FTO electrode and holes, leaving via the opposite side of the device. The direct electron pathways provided by the ZnO nanorods and adsorption of dye in the PANi network ensure the rapid collection of carriers generated throughout the device, and a rectification ratio of 3.21 under an illumination intensity of 100 mW cm⁻² is demonstrated, which is higher than the 1.12 for the FTO/ZnO nanorods:macroporous PANi network/Al heterojunction. The research is expected to open a new avenue for the development of highly efficient p–n heterojunctions and possibly serve as building blocks for future nanoelectronics.