How the world’s most efficient silicon solar cell reached a record 27.81% efficiency

Chinese solar manufacturer Longi has detailed the technical innovations behind its world-record silicon solar cell efficiency of 27.81%, certified by Germany’s ISFH and published in Nature. The cell employs a hybrid interdigitated back-contact (HIBC) design combining n-type and p-type contacts exclusively on the rear, eliminating front-side metal shading and enhancing light absorption. Key advancements include the use of passivated tunneling contacts, dielectric passivation layers, and edge passivation on high-resistivity half-cut M10 wafers to reduce carrier recombination and losses. A novel high-low temperature fabrication process enables simultaneous diffusion and deposition while passivating wafer edges in situ (iPET technology). Additional improvements involve a multilayer front surface stack of aluminum oxide and silicon nitride to optimize optical properties and suppress recombination, alongside an amorphous silicon layer whose thickness is carefully controlled and crystallized by pulsed green nanosecond laser to balance passivation and conductivity. The doping of the n-type poly