High Efficiency LED Designs Using Quantum Well Engineering
Achieving high efficiency LEDs with green, amber and longer wavelengths using III-nitride/II-IV-nitride heterostructures as the active media.
Although extensive research and development over the past two decades has resulted in close to 100% external quantum efficiency (EQE) of InGaN based blue light emitting devices, efficiency of the longer visible wavelength emitting devices has remained relatively low. Spontaneous polarization originating from the absence of inversion symmetry in the wurtzite structure and piezoelectric polarization caused by the lattice mismatch induced strain in InGaN quantum wells based light-emitting devices render internal electric field and concomitant localization of electron and holes in different regions of the QW. There is a need to address the efficiency issue in InGaN based green and longer wavelength emitting devices. The Global Light Emitting Diodes Market size stood at $85.8 billion USD in 2020, and is expected to hit $174.11 billion USD by 2027. As a result, addressing this issue proves to be a profitable opportunity.
Our team at The Ohio State University has developed a III-nitride/II-IV-nitride heterostructure to achieve high efficiency LEDs with green, amber and longer wavelengths. This approach takes advantage of increased flexibility to tune the quantum well active region to lower the emission wavelengths and increase the electron-hole wave function overlap to pave a new way to extend the InGaN quantum well LED emission wavelength without using high-indium-content InGaN. By doing so, the internal quantum efficiency is greatly improved.