Low‐Temperature Oxidation‐Processed Titanium Oxides as Dual‐Functional Electron‐Selective Passivation Contacts

Passivation contact (PSC), which simultaneously achieves high passivation quality and low contact resistivity, has been proven to be a delicate design to fabricate high‐efficiency solar cells (SCs). However, traditional PSC materials, that is, intrinsic a‐Si:H/doped a‐Si:H or tunnel SiO2/doped poly‐Si, overly rely on the complex procedures and have inevitable optical or Auger recombination losses. Herein, a novel low‐temperature oxidation (LTO) process is developed and an electron‐selective TiOx film (LTO‐TiOx) is fabricated, reaching a low‐effective surface recombination velocity of 13.7 cm s−1. The high‐quality passivation performance is mainly attributed to the chemical passivation of Ti–O–Si bonds and the surface carrier manipulation ability of the LTO‐TiOx film. Next, by adding a low work function (WF) layer of LiFx film, the surface band bending effect is formed and the contact resistivity of TiOx‐based PSC is also optimized. Furthermore, the dual‐functional LTO‐TiOx/LiFx electron‐selective PSC is integrated in Si SCs and a champion efficiency is achieved near 19% with an open‐circuit voltage near 640 mV. Finally, a comprehensive simulation analysis indicates a high efficiency of more than 22% based on LTO‐TiOx PSC, followed by a detailed roadmap of efficiency improvements, demonstrating its huge application potential in SCs.