AbstractSolar cells need efficient light absorption to achieve high efficiencies. In this paper, we present a study on the immersion effect of porous silicon (PS) in a Lithium Bromide (LiBr) aqueous solution, followed by thermal annealing at 100 °C for 30 min under nitrogen atmosphere on solar cells performances. The surface morphology was studied by Atomic Force Microscopy (AFM). All samples were analyzed by Fourier transmission infrared spectroscopy (FTIR) before and after LiBr immersion. Good electrical properties were observed after thermal annealing at 100 °C for 30 min under nitrogen atmosphere. The reflection spectra of PS, before and after LiBr treatment, performed in the 300‐1200 nm wavelength range, showed an important decrease of the reflectivity by this new treatment. A significant increase of the photoluminescence (PL) intensity was obtained after LiBr treatment. An enhancement of the light beam induced current (LBIC) as well as the internal quantum efficiency (IQE) were shown after LiBr treatment. I–V characteristics, under AM1.5 illumination, were improved owing to the increase of the minority carrier diffusion length (L) and an excellent enhancement of the surface recombination velocity (Vs) (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)