A route towards high-efficiency silicon heterojunction solar cells

In this work, we propose a route to achieve a certified efficiency of up to 24.51% for silicon heterojunction (SHJ) solar cell on a full-size n-type M2 monocrystalline-silicon Cz wafer (total area, 244.53 cm(2)) by mainly improving the design of the hydrogenated intrinsic amorphous silicon (a-Si:H) on the rear side of the solar cell and the back reflector. A dense second intrinsic a-Si:H layer with an optimized thickness can improve the vertical carrier transport, resulting in an improved fill factor (FF). In order to reduce the plasmonic absorption at the back reflector, a low-refractive-index magnesium fluoride (MgF2) is deposited before the Ag layer; this leads to an improved gain of short circuit current density (J(sc)). In total, together with MgF2 double antireflection coating and other fine optimizations during cell fabrication process, similar to 1% absolute efficiency enhancement is finally obtained. A detailed loss analysis based on Quokka3 simulation is presented to confirm the design principles, which also gives an outlook of how to improve the efficiency further.

Automated summary

This work proposes a route to achieve a certified efficiency of up to 24.51% for silicon heterojunction solar cell by mainly improving the design of the hydrogenated intrinsic amorphous silicon on the rear side of the solar cell and the back reflector. By optimizing the thickness of a dense second intrinsic a-Si:H layer and depositing a low-refractive-index MgF2 before the Ag layer, an improved fill factor and gain of short circuit current density are obtained. Together with MgF2 double antireflection coating and other fine optimizations, a similar to 1% absolute efficiency enhancement is finally obtained.