CuInS₂/ZnS-based QLED design and modelling for automotive lighting systems

This work reports the design, manufacturing and numerical simulation approach of a 6-pixel (4.5mm²/pixel) electroluminescent quantum dot light emitting device (QLED) based on CuInS₂/ZnS quantum dots as an active layer. Following a conventional thin-film deposition multilayer approach, the QLED device was fabricated. In addition, the electrical I-V curve was measured for each pixel independently, observing how the fabrication process and layer thickness have an influence in the shape of the plot. This experimental device fabricated, 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. Besides, it is worth highlighting that the simulator allows the possibility to study the influence of different parameters of the QLED structure like the junction capacitance between the distinct multilayer set. Specifically, we found that Anode-HIL interface capacitance has a greater influence in the I-V plot shape. That junction capacitance plays an important role in the current increase and the QLED turn-on value when a forward voltage is applied to the device. Thanks to the simulator, that influence could be put under control by the selection of the optimal thickness and transport layers during the experimental fabrication process. This work is remarkable since it achieves to fit simulation and experiment results in an accurate way for electroluminescent QLED devices; particularly the simulation of the device current, which is critical when designing the automotive electronics to control these new nanotechnology lighting devices in the future.