Opto-electronic properties of a TiO2/PS/mc-Si heterojunction based solar cell

Abstract In this work, we show the results of our investigation on the photoelectric properties of heterojunction solar cells based on Au/PS/mc-Si/Al and Au/TiO 2 /PS/mc-Si/Al structures. Porous silicon (PS) were prepared by an electrochemical etching process with different values of current density. The surface porosity was found to increase with the increase of current density. Pulsed laser deposition was used to deposit 80 nm TiO 2 thin films. Surface morphology and structural properties of TiO 2 /PS were characterized by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). An enhancement of the electrical properties of the TiO 2 /PS/mc-Si heterojunction was observed after coating with TiO 2 . As a consequence, the solar cell efficiencies increased from 1.4% for the uncoated PS/mc-Si structure to 5% for the TiO 2 coated one. Impedance spectroscopy confirmed the passivation effect of TiO 2 through the improvement of the elaborated cells’ electron lifetime and the formation of a TiO 2 /PS/Au heterojunction with the appearance of a second semi-circle in the Nyquist plot.