Fig. 1: Photoelectrical performance of HBC solar cells.

a Cross-sectional diagram of HBC solar cells. The substrate is n-type crystalline silicon (n-c-Si). The front side features anti-reflection coatings (ARC), and the rear side is divided into four regions, which are HSC, gap, ESC, and HSC + gap. The inserted transmission electron microscope image is the boundary of the HSC and gap region, named HSC + gap. b Current density-voltage (J-V) curves of our HBC solar cell have efficiencies of 26.74% and 27.09% for total area (ta) and designated illumination area (da), respectively. These measurements were performed at ISFH under standard test conditions. c Electrical loss (V_OC × FF loss) analysis of the three high-efficiency solar cells. Wherein the electrical loss is mainly represented by the recombination current density (J₀ with the ideality factor of 1 and 2) and the series resistance (R_S). The extracted values and equivalent circuits are described in Fig. S2. Detailed information on the recombination model has been reported in our previous work¹¹. The black dotted lines in the figure are the isometric contour, as demonstrated in Fig. S4. The magnitude of the triangular area enclosed by the three parameters indicates the strength of the solar cell electrical performance. Specifically, smaller area implies lower electrical loss, which benefits the photoelectric performance of the solar cell. d Short-circuit current density loss (J_SC loss) analysis of the three high-efficiency solar cells. The J_SC loss are mainly represented by the shading effect (J_shade, including loss cuased by electrode shading and electrical shading) and the optical evaluation on the front and rear sides (J_front and J_rear). The specific parameter values of the three solar cells are analyzed from respective external quantum efficiency (EQE) and reflection curves, as described in Fig. S5. Source data are provided as a Source Data file.