Pulsed-laser-deposited lead sulfide nanoparticles based decoration of porous silicon layer as an effective passivation treatment for multicrystalline silicon

•Passivation of multicrystalline silicon obtained using pulsed laser deposited PbS nanoparticles.•Optimization of both the optical and electronic properties of the multicrystalline silicon substrate through the variation of the PbS nanoparticles sizes.•Improvement of the minority carrier lifetime due to the passivation by the PbS nanoparticles (ie., 430 μs versus 40 μs for the bare porous silicon and 2.2 μs for the bare multicrystalline silicon). We report on the use of pulsed laser deposition (PLD) of PbS nanoparticles (PbS-NPs) on porous silicon layers in order to passivate multicrystalline silicon (mc-Si) substrates intended for solar cells applications. The porous silicon (PS) layer was first obtained through the electrochemical anodization of the mc-Si substrate, and then the PLD technique was used to decorate the PS layer by PbS-NPs at room temperature. By varying the number of laser ablation pulses (NLP) from 50 to 1200, the average size of the PbS-NPs was varied from ~2 nm to ~10 nm. The X-ray diffraction analysis has confirmed the crystalline quality of the PbS-NPs, whereas the transmission electron microscopy observations showed the uniform decoration of the PS by the PbS-NPs. By combining different characterization techniques, we were able to identify NLP = 200 as the optimal decoration condition that leads to the best passivation, in terms of the lowest surface reflectivity (of 15% at 500 nm wavelength), the highest PL intensity of the PS layer (centered around 633 nm) and the longest minority carrier lifetime (as long as ~430 µs versus 40 µs for the bare treated PS layer and 2.2 µs for the untreated bare mc-Si).