Investigating the influence of TCOs and tunneling dielectric layers on TOPCon solar cell performance

The Tunnel Oxide Passivated Contact (TOPCon) solar cell represents an advanced iteration of the first-generation PERT solar cell, renowned for its high power conversion efficiency. Performance of the TOPCon solar cells relies on characteristics of the dielectric material from which the tunneling occurs. In this study, performance of the Tunnel Oxide Passivated Contact (TOPCon) solar cells and the impact of various transparent conducting oxides and tunnelling oxide layers on them were accessed. The study involved a detailed analysis of key parameters, such as the use of TCOs (FTO, AZO, ZnO, ITO) as a passivation layer and optically transparent electrodes, in combination with different alternative tunnelling oxide dielectric layers (SiO ₂ , Al ₂ O ₃ , HfO ₂ , ZrO ₂ , and TiO ₂ ) by using the AFORS-HET simulation software. The results showed that existence of an ultra-thin oxide layer with low interface states density (D _it ≈ 1 × 10 ⁹ cm ^− 2 eV ^− 1 ), and pinhole density (D _ph < 1 × 10 ^− 6 ) suppressed carrier recombination at the rear surface. The optimum solar cell performance values were found to be V _oc = 693 mV, J _sc = 42.71 mA/cm ² , FF = 88.39%, and packing conversion efficiency (PCE) = 26.16% with an Al ₂ O ₃ tunnel dielectric layer.