The Polymer Society of Korea

Abstract

Precise control of droplet drying dynamics is key to tailoring film morphology in printed optoelectronic devices. In ink based manufacturing, uncontrolled evaporation often produces ring like deposition due to contact line motion. Here, we show that vacuum assisted drying enables scalable, chemical free control of contact line behavior in quantum dot droplets via ambient pressure. CdSe/ZnS droplets were dried under pressures from atmospheric to 0.48 kPa. Time resolved imaging revealed a transition from continuous depinning to complete pinning, from constant contact angle to constant contact radius behavior. Reduced pressure accelerated evaporation and strengthened capillary driven flow toward the contact line, promoting early particle accumulation that immobilized the line and confined material radially. These results identify ambient pressure as a tunable parameter for controlling drying and morphology, improving uniformity and reproducibility in droplet based additive manufacturing.