Highly flexible light emitting diodes based on a quantum dots-polymer composite emitting layer

In this work, we report highly flexible QLEDs based on a quantum dots-polymer composite emitting layer. Conventional quantum dot films exhibit cracks after rough bending. Herein, polymethyl methacrylate (PMMA) was doped into quantum dot solution, acting as binder for neighboring quantum dots. In addition, PMMA can be serving as an electron blocking layer due to its insulating property, and then balancing the charge recombination and improving device performance. The flexible QLEDs have excellent mechanical properties with an ultimate bend radius of 1.5 mm, and they show no significant performance degradation after 500 times bending with radius of 4 mm. The flexible QLEDs exhibit high performance with maximum luminance of 14880 cd/m2 and maximum current efficiency of 21.3 cd/A.