Jolywood (Taizhou) Solar Technology Co, the PV module manufacturing arm of major PV backsheet manufacturer Jolywood (Suzhou) Sunwatt Co said it had made a conversion efficiency breakthrough with n-type TOPCon (Tunnel Oxide Passivated Contact) high-efficiency bifacial solar cells.

The PV manufacturer had previously achieved a conversion efficiency of 23.2% at the end of 2019. The new 0.3% higher efficiency cell (23.5%) was achieved with an optimized homogeneous boron emitter with Al2O3/SiNx as passivation films and a metallization process for better contact, according to the company.

As a production ready process, Jolywood used n-type 158.75mm x 158.75 (G1) silicon wafers to achieve the record conversion efficiency.

The use of Ion implantation is usually applied to overcompensate an in-situ boron-doped TOPCon layer with phosphorus that can reduce leakage current and simplify fabrication steps for cells featuring passivated contacts.

Having previously developed and has ongoing R&D activities with IBC (Interdigitated Back Contact) cells that use ion implantation, Jolywood said that using ion implant with its TOPcon cell avoided the potential for leakage currents and hot spot risks, helping to provide improved output-power of 3-5Wp.

At the PV module level, Jolywood said that the bifacial passivating-contact module increased bifaciality, had lower degradation and a lower temperature coefficient than before.

The company did not reference any third-party independent body that may have verified the record efficiencies.