Black silicon with nanosized textures is very important to the diamond wire sawn (DWS) multicrystalline silicon (mc-Si) solar cell due to its low reflectivity. Normally the nanosized textures can be obtained by metal-assisted chemical etching (MACE) on the DWS mc-Si wafers. Here, we found that in order to improve the conversion efficiency of DWS mc-Si solar cell with nanosized textures, the textures’ morphologies must be modified by acid etching. The acid etching is the defect removal etching process. Our experimental results showed that the acid etching process influences not only the size and the reflectivity of the nanosized textures, but also the recombination velocities of the silicon wafers. A DWS mc-Si solar cell with modified nanosized textures was successfully obtained by MACE and suitable acid etching process, whose reflectivity is lower than that of a DWS mc-Si solar cell prepared by conventional acidic texturizing. The highest conversion efficiency of 19.07% was reached and a 0.6% conversion efficiency gain was obtained for a DWS mc-Si solar cell (15.6 cm × 15.6 cm), as opposed to the DWS mc-Si solar cell prepared by conventional acidic texturizing.

A series of ionic liquids based on trifluoroacetic acid, namely, [C_nmim][TFA] (n= 2, 3, 4, 5, 6) (1-alkyl-3-methylimidazolium trifluoroacetate), were designed and synthesized.