Effect of nanoporous silicon coating on silicon solar cell performance

The surface modification of silicon solar cells was used for improvement of photovoltaic characteristics of silicon solar cells. A screen-printed solar cell technology is used to fabricate n+-p silicon solar cell. Nanoporous silicon (PS) layer on n+-type Si wafers or on the frontal surface of (n+-p)Si solar cell was formed by electrochemical etching in HF-containing solution. The surface morphology, porosity, spectra of photoluminescence and reflectance of PS layers were analyzed. The photovoltaic characteristics of two silicon solar cell type with and without PS layer (PS/(n+-p)Si and (n+-p)Si cell) were measured and compared. The spectra of photosensitivity of cells were measured in the wavelength range of 300–1100 nm. An average reflection of the porous silicon layer, fabricated on a polished silicon surface, is decreased to 4%. A remarkable increment of the conversion efficiency by 20% have been achieved for PS/(n+-p)Si solar cell comparing to (n+-p)Si solar cell without PS layer. The results, related with improving of the performance of PS/(n+-p)Si solar cell, have been attributed to the effective antireflection and the wide-gap window role of nanoporous silicon on the silicon solar cell.