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 paper, green perovskite LEDs (PeLEDs) are fabricated on 50-μm thick polyimide substrates. Using colloidal 2-D 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 color saturation > 95%, in the Rec. 2020 standard gamut area. To demonstrate mechanical flexibility, the device functionality is tested by dynamic bending experiments down to 10 mm for up to 5000 cycles, resulting in device lifetime over 36 h in a glove box and a drop of ηCE and external quantum efficiency (ïext) as low as 15% and 18%, respectively. For the selective activation of multiple PeLEDs, 7×7 passive arrays on rigid and flexible substrates are demonstrated. Moreover, preliminary results of active matrices show the compatibility of PeLEDs with oxide-based thin-film transistors (TFTs) for display applications.