Preparation of Plasmonic Ag and Au Nanoparticle Interfaces for Photocurrent Enhancement in Si Solar Cells

Nanoparticle (NP) arrays of noble metals strongly absorb light in the visible to infrared wavelengths through resonant interactions between the incident electromagnetic field and the metal's free electron plasma. Such plasmonic interfaces enhance light absorption and photocurrent in solar cells. We report here broadband plasmonic interfaces consisting of silver nanoparticles (NPs) formed by depositing by e-beam evaporation a thin film of Ag followed by dewetting process under thermal annealing. The NP interface yields a clear photocurrent enhancement (PE) in thin film silicon devices. For coatings produced from Ag NPs, an optimal value of 15% surface coverage (SC) was observed. Scanning electron microscopy of interface morphologies revealed that low SC is resulting in broadband PE; while at higher coverage, strings and clusters are formed and caused red shifting of the PE peak and a narrower spectral response. The multi-physics impacts of size and radius distribution of plasmonic-NPs (including Ag and Au) were also studied. For optimal PV performance, a parametric analysis was performed for system sizes of
$\boldsymbol{(3\times 3,\ 5\times 5,\ 7\times 7)}$
, and radii varying from 10 to 150 nm. Total spectral heat absorbed was also investigated by integrating total spectral heating from 300 nm to 1200 nm. The optimum performance for a Schottky-like device were obtained for a 70 nm radius and a surface coverage of 22.72 NP/µm
²
, revealing a maximum short circuit current gain of about 47 % when compared to bare silicon solar cell.