Publicação
QUANTUM DOTS FOR OPTOELECTRONIC APPLICATIONS. CHARACTERIZATION OF PEROVSKITE CAPPED LEAD SULPHIDE QUANTUM DOTS THROUGH THIN-FILM TRANSISTORS
| Resumo: | Halide perovskite materials have emerged as promising semiconductors for optoelectronic applications, including photovoltaic cells and thin-film transistors (TFTs), due to their tuneable bandgap and high carrier mobility. However, optimizing charge transport and stability in these materials remains a challenge. This thesis investigates the functionaliza- tion of lead sulphide (PbS) colloidal quantum dots (QDs) with halide perovskite ligands as a strategy to enhance charge carrier mobility and passivate surface defects in TFTs. A comprehensive study regarding the synthesis of quantum dots through hot-injection method, followed by ligand exchange procedure from initial oleic acid chains to perovskite ones, and thin-film transistor fabrication in a staggered bottom-gate, top-contact configu- ration was conducted. Optical, morphological, and electronic characterizations, including optical spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transistor electrical characterization mea- surements, were performed to evaluate the effects of perovskite functionalization on PbS QDs. The results indicate that perovskite-capped PbS QDs exhibit ambipolar and im- proved charge transport properties, reaching hole mobilities up to 8.81 × 10−2 cm2 · V−1s−1 in dark conditions, by using three depositions of the semiconductor material. We also re- port an optimal concentration of 104 mg · mL−1 for the semiconductor in study, among the ones analysed. Under light conditions, we report mobilities up to 3.690 × 10−1 cm2 · V−1s−1, at 1 spin with 104 mg · mL−1, making this semiconductor layer a promising candidate for next-generation semiconductor layers in TFTs. This research contributes to the development of quantum dot-perovskite hybrid mate- rials, offering new insights into material optimization strategies for optoelectronic device applications. |
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| Autores principais: | Almeida, Diogo Alexandre Ribeiro de |
| Assunto: | Optoelectronics Photovoltaics Thin-Film Transistors Colloidal Quantum Dots Metal Halide Perovskite Ligand Exchange |
| Ano: | 2025 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade Nova de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório Institucional da UNL |
| Resumo: | Halide perovskite materials have emerged as promising semiconductors for optoelectronic applications, including photovoltaic cells and thin-film transistors (TFTs), due to their tuneable bandgap and high carrier mobility. However, optimizing charge transport and stability in these materials remains a challenge. This thesis investigates the functionaliza- tion of lead sulphide (PbS) colloidal quantum dots (QDs) with halide perovskite ligands as a strategy to enhance charge carrier mobility and passivate surface defects in TFTs. A comprehensive study regarding the synthesis of quantum dots through hot-injection method, followed by ligand exchange procedure from initial oleic acid chains to perovskite ones, and thin-film transistor fabrication in a staggered bottom-gate, top-contact configu- ration was conducted. Optical, morphological, and electronic characterizations, including optical spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transistor electrical characterization mea- surements, were performed to evaluate the effects of perovskite functionalization on PbS QDs. The results indicate that perovskite-capped PbS QDs exhibit ambipolar and im- proved charge transport properties, reaching hole mobilities up to 8.81 × 10−2 cm2 · V−1s−1 in dark conditions, by using three depositions of the semiconductor material. We also re- port an optimal concentration of 104 mg · mL−1 for the semiconductor in study, among the ones analysed. Under light conditions, we report mobilities up to 3.690 × 10−1 cm2 · V−1s−1, at 1 spin with 104 mg · mL−1, making this semiconductor layer a promising candidate for next-generation semiconductor layers in TFTs. This research contributes to the development of quantum dot-perovskite hybrid mate- rials, offering new insights into material optimization strategies for optoelectronic device applications. |
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