Self-assembled molecules as efficient selective contacts in translucent quantum-dot light emitting diodes
[eng] Since the last two decades, nanotechnology has been revolutionary for representing small solutions to the big problems. Nanoscience and Nanotechnology spread from the area of Electronics, Energy and Environment to Biomedicine, Food or Textile where it has made possible to selectively target th...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2023 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/205321 |
| Acceso en línea: | https://hdl.handle.net/2445/205321 http://hdl.handle.net/10803/689649 |
| Access Level: | acceso abierto |
| Palabra clave: | Nanotecnologia Nanocristalls Electrònica quàntica Nanotechnology Nanocrystals Quantum electronics |
| Sumario: | [eng] Since the last two decades, nanotechnology has been revolutionary for representing small solutions to the big problems. Nanoscience and Nanotechnology spread from the area of Electronics, Energy and Environment to Biomedicine, Food or Textile where it has made possible to selectively target the cells to repair the damaged genes. It has also made possible to convert more sunlight into energy with efficient solar panels. Nanostructured materials make faster and more efficient microchips. It also contributes to make biosensors to detect pollutants in bodies. Today, nanomaterials have made possible to fabricate the LEDs of different colours. Colloidal quantum dots technology has drawn a huge attention in the academia and industry since last decade. Quantum dots are also called “Artificial Atoms” because they have discrete energy levels just like atoms. QDs are zero dimensional particles showing quantum confinement effect which means that their size comparable to Bohr radius and their colour can change with their size which is typically between 2-10 nm. On the other hand, these materials show excellent optical properties including high absorption, strong and narrow emission with high colour purity making them suitable for various applications. Perovskites are crystalline materials with the structure of calcium titanium oxide. They are extensively used for several applications because of their easy manufacturing process, abundance, low cost, and great flexibility. Metal halide perovskites are popular for their vast range of application in optoelectronic devices while metal oxide perovskites are widely used in chemical, electrochemical and photocatalysis. Self-assembled molecules (SAMs) are a class of materials which can attach to any substrate modifying the work function of the electrode for their diverse application. They consist of three components including terminal group, spacer group and anchoring group. SAMs are used to make organic and perovskite solar cells with better efficiency and stability. Nowadays, their application in perovskite LEDs have also emerged. Light emitting diodes (LEDs) works on the principle of electroluminescence. When a forward bias is applied to the device between the anode and cathode, the electrons flows towards the cathode and the holes towards anode. Majority charge carriers from the corresponding layers flows towards the emissive layer (if they can cross the barriers) by making the emissive layer negatively charged. Direct band gap semiconductors lead to the energy difference as the electron recombines to the holes by radiative recombination leading to the generation of photons. By the annihilation of an electron and hole, one photon generates. The band gap and chemical structure of the emissive material determines the color of the electroluminescence which is released from the device. The present thesis is focused on the synthesis of perovskite nanocrystals and their application in perovskite nanocrystal LEDs (PeLEDs) and the preparation of QDLEDs based on cadmium selenide QDs. We have used SAMs as hole transporting layer in PeLEDs which is a good alternative to the conventional hole transport materials (HTMs). SAM are good for the overall performance of devices including luminance and stability but also promotes thin sized LEDs. With this regard, we have also employed a thin layer of PDINO as electron transport material (ETM) for fabricating red QDLEDs in combination with commercial CdSe@ZnS quantum dots as emissive material. Finally, we have performed doping of a rare-earth element Dysprosium (Dy) in the methylammonium bromide (MAPbBr3) Perovskite lattice at different concentration to find the optimum for our LEDs. |
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