Investigation of anti-reflection-coating stacks for silicon heterojunction solar cells

High-efficiency silicon heterojunction solar cells, like the Panasonic HIT cell [1], use transparent conductive oxides (TCO) as anti-reflection layers. We investigated whether a single TCO layer or a two layers ARC stack is the better option for such a cell. Therefore we simulated the reflection and transmission properties of single indium tin oxide (ITO)-layers with various optical constants and layer systems with two different anti-reflection coatings (ARC). We also calculated the short-circuit current density (Jsc) for these systems. We found out that with a second anti-reflection layer the standard weighted reflectance (SWR) can be reduced by 5 % compared to single layers coatings. The best calculated Jsc for non-textured surfaces was 35.7 mA/cm2. With a texture we consider an additional Jsc gain of approx. 3 mA/cm2 approaching 39 mA/cm2.