Development of sol-gel derived gahnite anti-reflection coating for augmenting the power conversion efficiency of polycrystalline silicon solar cells

The present research is focused on developing ZnAl₂O₄ (gahnite) spinel as an antireflection coating material for enhanced energy conversion of polycrystalline silicon solar cells (PSSC). ZnAl₂O₄ has been synthesized using dual precursors, namely aluminum nitrate nonahydrate and zinc nitrate hexahydrate in ethanol media. Diethanolamine has been used as a sol stabilizer in sol-gel process for ZnAl₂O₄ nanosheet fabrication. ZnAl₂O₄ nanosheet was deposited layer-by-layer (LBL) on PSSC by spin coating method. The effect of ZnAl₂O₄ coating on the physical, electrical, optical properties and temperature distribution in PSSC was investigated. The synthesized antireflection coating (ARC) material bears gahnite (ZnAl₂O₄) spinel crystal structure composed of two dimensional (2D) nanosheets. An increase in layer thickness proves the LBL deposition of ARC on the PSSC substrate. The ZnAl₂O₄ 2D nanosheet comprising ARC on the PSSC was tested and it exhibited a maximum of 93 % transmittance, short-circuit photocurrent of 42.364 mA/cm² and maximum power conversion efficiency (PCE) 23.42 % at a low cell temperature (50.2 °C) for three-layer ARC, while the reference cell exhibited 33.518 mA/cm², 15.74 % and 59.1 °C, respectively. Based on the results, ZnAl₂O₄ 2D nanosheets have been proven as an appropriate ARC material for increasing the PCE of PSSC.