Titanium oxynitride electron-selective contact for crystalline silicon solar cells

Abstract

Wide-bandgap metal compound-based carrier-selective contacts are being intensively developed to mitigate the carrier recombination losses at the contact regions of crystalline silicon (c-Si) solar cells. In this work, magnetron sputtered titanium oxynitride (TiOxNy) is exploited as an electron-selective contact for c-Si solar cells. We investigate the effect of various deposition parameters (N2 concentration, power, and pressure) on the optoelectronic properties of TiOxNy films. The optimized TiOxNy film features a low resistivity of 9 × 10−4 Ω cm and high transmittance. The surface passivation and contact resistivity of TiOxNy films on c-Si were also investigated. The results demonstrate that TiOxNy can effectively serve as an electron-selective contact for c-Si solar cells due to its low WF (4.15 eV) and low contact resistivity of 9.4 mΩ cm2 on c-Si. By implementing a full-area TiOxNy rear contact, a champion efficiency of 20.2% is obtained on the n-type c-Si solar cell, representing an absolute efficiency gain of 4.4%.