Plasmonic Silver Structures for Improved Perovskite Photovoltaic Performance

In photovoltaics, photon harvesting is one of the important factors for the enhancement of the power conversion efficiency. The prime factor for the device performance is optical absorption by the active layer. Photon harvesting by the active layer can be enhanced by indirect means such as plasmonic light harvesting. In this way, the light is focused towards the active layer to improve the effective light absorption. The mechanism by which light trapping by the metallic nano-structures whose dimension usually less < 40nm and generates local surface plasmon resonance (LSPR) which acts like a sub-wavelength antennas as a result plasmonic near field is coupled to the active layer. In the other case, metallic nanostructure having dimension > 40 nm behaves like sub-wavelength scattering center and hence traps freely propagating plane wave of incident light and couples to the semiconducting layer. Therefore, it is possible to achieve light trapping by introducing metallic nanostructures at the device interfaces. In this work, poly-dispersed metallic nanostructures (silver nanoparticles AgNP) were embedded at the active layer/cathode interface to study the perovskite photovoltaic device performance. It is observed that device with AgNP at the active layer/cathode interface showed significant enhancement in optical absorption. As a result device with Ag metallic nanostructure showed significant improvement in short circuit current. It is observed that metallic nano-structures at cathode interface aids in light trapping and also reduction in series resistance. These coupled effects of optical and electrical enhancement tend to improved power conversion efficiency in the device.