• • Inkjet-printed OLEDs achieve external quantum efficiencies of 15–20% for fluorescent emitters and >25% for phosphorescent systems, matching vacuum-deposited benchmarks at laboratory scale; industrial relevance lies in enabling roll-to-roll manufacturing with >90% material utilization versus <20% for evaporation.
• • Stable jetting requires ink viscosity of 1–20 mPa·s and surface tension of 25–45 mN/m, with Ohnesorge number Z between 0.1 and 1; outside this window, satellite droplets and nozzle clogging reduce yield below 70%, directly impacting cost-per-panel.
• • The coffee-ring effect causes pixel non-uniformity with thickness variation exceeding 15% across a 50 µm pixel; binary solvent systems (e.g., cyclohexanone + anisole) and substrate temperatures of 40–60 °C suppress this to <5%, critical for consistent color coordinates (ΔE < 0.01).
• • Printed OLED lifetimes (T95) exceed 1,000 hours at 1,000 cd/m² for optimized multilayer stacks, but interlayer dissolution during sequential printing reduces this by 30–50% without cross-linked hole-transport layers; this dictates the need for orthogonal solvents and thermal cross-linking at 150–180 °C.