Flexible Green Perovskite Light Emitting Diodes

Flexible perovskite light-emitting diodes (LEDs) have attracted increasing interest to realize ultrathin, light weight, highly conformable and nonfragile vivid displays. Solution-processed lead halide perovskite offers numerous distinctive characteristics such as pure emission color, tunable bandgaps, and low fabrication cost. In this letter, green perovskite LEDs (PeLEDs) are fabricated on 50 μm thin polyimide substrates. Using colloidal 2D formamidinium lead bromide perovskite emitter, the PeLEDs show a high current efficiency (ηCE) of 5.3 cd A−1 with a peak emission at 529 ± 1 nm and a narrow width of 22.8 nm. The resultant green emission shows a record high color saturation, > 95%, in the Rec. 2020 standard gamut area. To demonstrate their mechanical flexibility, the device functionality is proved by dynamic bending experiments down to 10 mm up to 5000 cycles, resulting in device lifetime over 36 h in glove box and a drop of ηCE and external quantum efficiency (ηxt) as low as 15 % and 18 %, respectively.