Copper-Diffused AgInS₂ Ternary Nanocrystals in Hybrid Bulk-Heterojunction Solar Cells: Near-Infrared Active Nanophotovoltaics

We have grown copper-diffused AgInS2 ternary nanocrystals in order to introduce the nanoparticles in organic/inorganic bulk-heterojunction devices for photovoltaic applications. Here, copper diffuses to vacant sites and improves conductivity of the nanocrystals. Upon use of such copper-diffused nanoparticles that led to a decrease in internal resistance of sandwiched devices based on the bulk-heterojunction, there has been a marked improvement in short-circuit current under white light illumination. Due to a red-shift in the optical absorption spectrum of the nanoparticles upon copper diffusion, the devices moreover acted as near-infrared (IR) active photovoltaic solar cells. From current-voltage characteristics and impedance spectroscopy of the devices, we optimized performance of the photovoltaic devices. To do so, we have varied the content of diffused copper in AgInS2 nanoparticles and also the weight-ratio between the polymer and the nanoparticles of the hybrid bulk-heterojunction devices.