Fig. 1. (Color online) Illustration of multilayer perovskite LED device and the heating-assisted vacuum deposition (HAVD) method to deposit the perovskite film.

Fig. 2. (Color online) (a) PL spectra and (b) corresponding PLQY of CsPbBr₃ films deposited on glass substrates with different heating temperatures. (insets: photographs of CsPbBr₃ films deposited on glass base under ultraviolet (UV) light) (c) Photographs of CsPbBr₃ films deposited on flexible polyimide film under UV light. (d) XRD spectra of CsPbBr₃ films with heating temperatures of RT and 100 °C.

Fig. 3. (Color online) (a) UV–Vis absorption, (b) Absorption coefficient as a function of energy, and (c) Time-resolved photoluminescence decay curves of the RT- and 100 °C-based CsPbBr₃ films. (d) Current density-voltage characteristics of electron-only devices with CsPbBr₃ emitting layer deposited at RT and 100 °C.

Fig. 4. (Color online) AFM images CsPbBr₃ perovskite films deposited on ITO/PEDOT:PSS/poly-TPD underlayer with different heating temperatures of (a) room temperature, (b) 80 °C, (c) 100 °C, and (d) 120 °C.

Fig. 5. (Color online) LED device performance. (a) Current density and (b) luminance versus driving voltages and (c) EQE as a function of current density for the LEDs under different heating temperatures. (d) Normalized EL spectrum of LEDs at an applied voltage of 4 V (inset: a photograph of a device).

Fig. 6. (Color online) Luminance and EQE as a function of current density of (a) CsPb(Br/I)₃ and (b) CsPb(Cl/Br)₃ LEDs with RT- and 100 °C-based substrates. Normalized EL spectra of (c) CsPb(Br/I)₃- and (d) CsPb(Cl/Br)₃ LEDs with RT- and 100 °C-based substrates. (inset: photographs of devices)

Table 1. Time-resolved PL data of CsPbBr₃ films deposited at RT and 100 °C.