Modelling and characterization of quantum dots as QLED devices for automotive lighting systems

Resumen

The automotive industry is undergoing three technological and social revolutions that are shaping the greatest ever upheaval in transportation i.e. electrification, autonomous vehicles, and digital mobility. In the frame of these revolutions, automotive lighting systems play an important role. Indeed, lighting in the automotive world has undergone a radical change in recent years thanks to Light Emitting Devices (LEDs). Apart from the consumption and the long useful life that LEDs can offer to automotive lighting systems, style is also imperative in vehicle designs and particularly in lighting products. The current and future trend in the automotive world is to achieve even greater lighting surfaces. However, the current LED technology formed by discrete devices of point light sources makes this task very complex and expensive. Nowadays, a nanomaterial called quantum dots (QDs) could solve the issues described above effectively in the automotive field. QDs are nanocrystal semiconductors where electrons are confined in a region of space of nanometric dimensions. This implies the existence of a quantum confinement in the three dimensions of space. Optoelectronics is among the multiple applications that these groups of atoms can offer us. Specifically, LED lighting devices based on quantum dots (quantum dot LEDs), known by their acronym QLED, offer a promising future as a new generation of lighting devices. Therefore, this work reports the design, manufacturing and numerical simulation approach of an electroluminescent quantum dot light emitting device (QLED) based on quantum dots as an active layer. In addition, the electrical I-V curve was measured, observing how the fabrication process and layer thickness have an influence in the shape of the plot. This experimental device enabled us to create a computational model for the QLED based on the Transfer Hamiltonian approach to calculate the current density J(mA/cm2), the band diagram of the system and the accumulated charge distribution. Thanks to the QLED simulator developed, it would be possible to model the device and anticipate the electrical performance in a theoretical design step before going to QLED manufacturing at the laboratory. Eventually, particular automotive lighting system demonstrators were designed to integrate the theoretical and experimental research carried out in an industrial automotive product.