Aesha P. Patel^1,2, Ryan Muzzio², Matthew R. Young², Robert Morrissey², Suresh Chaulagain¹, B. Edward Sartor², Prabodika N. Kaluarachchi¹, Christian Velez², Joshua A. Brown², Joel N. Duenow², Stephen Glynn², Michael J. Heben¹, Zhaoning Song¹, Nikolas J. Podraza¹, Adam B. Phillips¹, Randy J. Ellingson¹, Matthew O. Reese^2
1University of Toledo, Toledo, OH
²National Laboratory of the Rockies, Golden, CO
CdTe-based thin-film solar cells, mainly Cd(Se,Te) (CST), were fabricated directly on 150 m Ceria-doped Corning 0214 glass to investigate the role of front contact engineering on device performance in the absence of conventional soda lime substrates. A systematic matrix of four transparent conducting oxides (TCOs) – Cadmium Stannate (Cd₂SnO₄, CTO), Aluminum-doped Zinc Oxide (AZO), Indium Tin Oxide (ITO), Indium Zinc Oxide alloy (IZO)) – combined with two n-type emitters (Magnesium Zinc Oxide (MZO) and Indium Gallium Oxide (IGO)) was evaluated to identify front contact combinations that balance optical transparency, electrical conductivity, and chemical stability under high-temperature (HT) processing. ‘Haacke’ figure-of-merit, derived from optoelectronic characterization, was used to rank front contact performance pre- and post-HT CST processing. Complementary dynamic secondary ion mass spectrometry (D-SIMS) and spectroscopic ellipsometry analyses were performed to assess elemental diffusion and interfacial mixing originating from the front contacts. Correlation of these interfacial characteristics with device performance reveals recombination-limited behavior for chemically unstable interfaces. These results establish front contact chemical stability as one of the key design parameters for high-efficiency CST solar cells on ultra-thin glass substrates.