Improving the passivation and the reflectance uniformity of SiNx anti-reflection coating by using the SiOx passivation paste

In our previous work, we developed a low-cost AlOx passivation paste and applied the printed AlOx layer to our passivated emitter and rear cell (PERC) product, named ExcelTon™-Cell-III. Based on the same organic system of the AlOx passivation paste, in this paper, we further develop a SiOx passivation paste and print it on the common SiNx single-layer (SL) anti-reflection coating (ARC) deposited by plasma enhanced chemical vapor deposition (PECVD). The quality of ARC, in terms of front-side passivation and reflectance uniformity, was improved by applying the extra printed SiOx layer. By using this dual-layer (DL) ARC, i.e. the printed SiOx/PECVD-deposited SiNx stack layer, the efficiency of PERC cells reached 20.73 %, which was 0.1 % higher than that of the reference cells (i.e. the PERC cells with PECVD-deposited SiNx SL ARC). This 0.1 % efficiency gain mainly came from the increases in Voc of 1.1 mV and in Isc of 16 mA, attributing to higher blue response of the DL ARC cells than that of the reference cell. We believe that the cell efficiency can be further increased by optimizing the thickness and the refractive index of each layer in this DL ARC.