Fig. 1. (Color online) Process flow of CSS.

Fig. 2. (Color online) (a) CSS setup using an electrically heated Ta foil; (b) simulated temperature distribution of the Ta foil under constant current; (c) foil temperatures under different currents with 10 s heating time; (d) the temporal profile of the evaporation rate and Ta foil temperature; (e) CSS evaporation rate of NPB films of various thicknesses from 50 to 500 nm as a function of Ta foil temperatures; (f) AFM image of a CSS-deposited NPB thin film; (g) AFM image of a VTE-deposited NPB film; (h) simulated and measured thickness profile of a CSS-deposited film from a 25 mm donor at a 1 mm gap; (i) film uniformity dependence on the donor-substrate gap and the donor dimensions; and (j) simulated thickness profile of a CSS-deposited film from a 2.5 m donor at a 20 mm gap.

Fig. 3. (Color online) (a) CSS using a curved Ta foil; (b) schematics of CSS deposition on curved surfaces; (c) CSS-deposited NPB film on a curved stainless-steel piece; (d) fluorescent image of CSS-deposited NPB on PMMA; and (e) UV-Vis absorption spectra of CSS-deposited NPB at different locations of the PMMA substrate.

Fig. 4. (Color online) (a) Radiation-heating CSS setup using a halogen bulb for device fabrication; (b) large-area radiation-heating CSS apparatus with a halogen lamp module; and (c) heating profile of the setup in (a) with a 250 W halogen bulb.

Fig. 5. (Color online) (a) The molecular structure of materials used for device fabrication; (b) device energy diagrams; (c) EQE vs. current density and (d) current density vs. voltage of blue OLEDs using CSS- and VTE-deposited NPB layers; and (e) current density vs. voltage plot of hole-only devices.

Table 1. Peak temperatures and evaporation rates in CSS at different currents.