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Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/212302
Inkjet printing next-generation flexible devices: memristors, photodetectors and perovskite LEDs
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[eng] New pressures due to emerging trends in device manufacturing are driving research efforts in new materials and manufacturing processes to achieve new combinations of properties, including capabilities such as physical and chemical sensing, conductivity, flexibility, transparency and those related to the internet of things. To face these challenges, printed electronics allows the deposition of next generation materials in ink form, at low cost, with the potential for scalable manufacturing.
Inkjet printing is a solution-based deposition technology that allows the deposition of a multitude of functional materials. Thanks to its ability to form patterns digitally, device geometry can be defined without the need for a mask or photolithographic processes, reducing manufacturing costs and enabling rapid prototyping of device architectures. Inkjet printing can be used to manufacture complete device structures, or to deposit innovative materials as a complement to other more established deposition technologies.
This thesis tries to show the versatility of inkjet printing as a device manufacturing technology to address future challenges. After the study and validation of various families of nanostructured materials printed by inkjet, three different types of devices are manufactured and characterized. The devices cover several application fields-, highlighting the adaptability of inkjet printing: h-BN 2D memristors, metal oxide nanoparticle photodetectors, and light emitting diodes (LEDs).
The first experiments in this thesis deal with 2D inkjet printed h-BN nanoflake memristors for hardware security applications. Memristors are a family of devices whose electrical resistance can be adjusted by electrical manipulation. Although they have shown promising results as information storage units, the applicability of memristors is still subject to their limited device-to-device and cycle-to-cycle repeatability. In this thesis, the inherent stochasticity of memristors is exploited for use as true random number generators (TRNGs) and their application as physical non-clonable functions (PUFs).
Next, inkjet printed metal oxide nanoparticle photodetectors are demonstrated. As wide-bandgap materials, metal oxides can play a promising role in selective, transparent, mechanically flexible, and low-cost UV photodetectors.
In the final sections, the rapidly developing field of perovskite LEDs (PeLEDs) is surveyed, focusing on inkjet printing of CsPbBr3 inorganic perovskite quantum dot LEDs. Although efforts in the PeLEDs literature have focused on achieving record efficiencies
with lab-scale techniques such as spin coating, few researchers have demonstrated scalable fabrication technologies for perovskite LEDs through solution processing such as inkjet printing. Here, the feasibility of inkjet printing is validated by showing fully printed PeLEDs (except the contacts) on flexible and rigid substrates, achieving pure green emission centered at 517 nm with a narrow half maximum down to 22 nm, consistent with the literature results of perovskite layers obtained by more established techniques, demonstrating that the properties of the perovskite layers are maintained in the inkjet deposition process. In this thesis, luminances of up to 17920 cd/m2 have been achieved for devices manufactured using a combination of thermal evaporation and inkjet, and of up to 324 cd/m2 for fully inkjet printed structures. In addition, low-temperature post-processing inorganic metal oxide transport layers are demonstrated, which replace widely used organic materials as a validation step towards more stable fully inorganic device structures.
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GONZÁLEZ TORRES, Sergio. Inkjet printing next-generation flexible devices: memristors, photodetectors and perovskite LEDs. [consulta: 11 de desembre de 2025]. [Disponible a: https://hdl.handle.net/2445/212302]