Silver catalyzed nano-texturing of silicon surfaces for solar cell applications

We report a relatively simple process for fast nano-texturing of p-type (1 0 0) silicon surface using silver catalyzed wet chemical etching in aqueous hydrofluoric acid and hydrogen peroxide solution at room temperature. In this approach, a fine textured black surface was achieved in about 15–30 s duration with reflectivity less than 4% in 400–1000 nm range. The reflectivity versus texturization time has been investigated and co-related with morphological characteristics of the nano-textured-silicon (nT-Si) surfaces. The nano-texturization process is also applicable in multi-crystalline silicon. Further, n+–p–p+ structured solar cells have been fabricated on such nT-Si substrates following the standard fabrication protocol. Significant improvement in short circuit current density (>20%) and efficiency (∼1.25% absolute) has been achieved compared with planar control cell without deterioration of other performance parameters (such as open circuit voltage and fill factor). Light beam induced current measurements have also been carried out to show the spatial distribution of the light trapping and current in the planar and the nT-Si solar cells.

Rλ versus λ curves of polished (CMP), alkaline texture (aT-Si), nano-texture (nT-Si; prepared for different texturization times) and nT-mc-Si surface. The curves are identified by numbers (1) CMP, (2) aT-Si, (3) nT-Si (15 s), (4) nT-Si (30 s), (5) nT-Si (45 s), (6) nT-Si (60 s), (7) nT-Si (90 s), (8) nT-Si (120 s) and (9) nT-mc-Si (30 s). The inset shows the variation of average Rλ (in the 400–1000 nm range) of different nT-Si surfaces with increasing texturing time.Figure optionsDownload as PowerPoint slideHighlights
► Silver catalyzed wet nano-texturing of silicon is a simple, fast and low cost process.
► Fine textured black surface with reflectivity <4% in 400–1000 nm is achieved.
► Ag-catalyzed nano-texturing is also applicable in multi-crystalline silicon.
► Nano-texturing improves Jsc significantly (>20%) without affecting Voc and FF.
► Nano-texturing process can be adopted in the standard cell fabrication protocols.