Effects of 2.85 nm Si Nanoparticles on AZO/n+/p c-Si Thin Film Solar Cell

In this work the effects of 2.85 nm colloidal Si nanoparticles are studied on AZO/n+/p c-Si thin film solar cells. Silicon nanoparticle volumes from 200-1000\ \mu \mathrm{L} are drop-casted on AZO/n+/p-Si solar cells in a 5-step sequence. Results show significant reflectance reduction for wavelength ranging between 300-600 nm, with small reflectance increase between 600-900 nm wavelengths. External quantum efficiency shows that short circuit current, Jsc, improves from ~17.97 mA/cm2 for reference cell to ~18.13 mA/cm2 after second drop-casting sequence (@ 400\ \mu \mathrm{L} volume), followed by the drop in Jsc for the rest of drop-casting sequences. After excluding reflectivity effects, the results show presence of added parasitic losses for drop-casting volumes above 400\ \mu \mathrm{L}. Some of these losses can be attributed to low quantum yield of nanoparticles, luminescence in isotropic direction, unfavorable scattering, parasitic absorption, etc. It is instrumental to identify different factors contributing to gains as well as the losses in quantum efficiency of a solar cell, to optimize the use of Si nanoparticles in thin film solar cells.