Effect of Seed Layers on Morphology and Optoelectronic Properties of IZO/Ag/IZO Multilayer Transparent Electrodes

Ultrathin silver‐based dielectric/metal/dielectric (DMD) transparent electrodes offer a promising route to simultaneously achieve high optical transparency and low electrical resistance in next‐generation silicon heterojunction solar cells. However, poor Ag wettability on oxide surfaces leads to island growth, increased surface roughness, and degraded optoelectronic performance. In this work, we developed IZO/X/Ag/IZO (35/2/8/35 nm, X = Cu, Ti, Sn) multilayer transparent electrodes deposited on glass substrates by RF and DC magnetron sputtering. The influence of the ultrathin seed layer on structural, morphological, optical, and electrical properties was systematically investigated before and after thermal annealing at 200 °C for 30 min in an N ₂ atmosphere. Grazing‐incidence X‐ray diffraction revealed nanocrystalline Ag (111) with crystallite sizes of 7.0–7.8 nm in the seed‐free, Cu‐, and Ti‐seeded films, whereas the as‐deposited Sn‐seeded film is dominated by a reflection tentatively assigned to an Ag–Sn intermetallic (Ag ₄ Sn); after annealing, its Ag coherent domain size (16.1 nm) exceeds the nominal Ag thickness, indicating Ag dewetting. Field‐emission scanning electron microscopy of the top IZO surface showed the finest and most uniform texture for the Cu‐seeded stack, which indirectly indicates suppressed Ag islanding. Among all the investigated electrodes, the annealed Cu‐seeded structure achieved the most favorable optoelectronic performance, combining an average visible transmittance of 80.24% (400–800 nm), and a sheet resistance of 15.1 Ω/sq. The corresponding Haacke figure of merit (FOM = T ¹⁰ /R _s ) reached 7.32 × 10 ⁻³  Ω ⁻¹ , approximately 28% higher than the annealed seed‐free reference; as both films have similar sheet resistance (~15  Ω/sq), this gain arises mainly from the higher transmittance. These findings indicate that for the 2 nm seed thickness and deposition conditions examined, Cu is the most effective of the three seeds for improving Ag growth and the optoelectronic performance of IZO/Ag/IZO electrodes for solar cell applications.