Bendable III-N Visible Light-Emitting Diodes beyond Mechanical Flexibility: Theoretical Study on Quantum Efficiency Improvement and Color Tunability by External Strain

We show that bending of flexible light-emitting diodes based on polar group III–V nitride structures can function as more than mechanically flexible devices through numerical studies. Controlled external bending can improve internal quantum efficiencies and electron-to-photon conversion efficiencies. Moreover, emission wavelength and color can be changed using active polarization control with external bending strains. We show that applying external strain on InGaN/GaN quantum-well (QW) heterostructures can mitigate or enhance the quantum-confined Stark effect. Significant IQE improvement (≥10%) is estimated by introducing external strain with concave-side up bending of flexible heterostructures. We also show significant wavelength shifts in peak emission. Especially, the In 0.35 Ga 0.65 N QW can be tuned in the overall visible spectral range by choosing different curvatures and bending modes. We have suggested the concept of a photoelectromechanical device that can emit different colors depending on the applied external strain varying from red to blue, enabling white light generation with the same active region consisting of QWs with a constant indium mole fraction.