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| DC 欄位 | 值 | 語言 |
|---|---|---|
| dc.contributor.advisor | 陳永芳(Yang-Fang Chen) | |
| dc.contributor.author | KRISHNA PRASAD BERA | en |
| dc.contributor.author | 奎席納 | zh_TW |
| dc.date.accessioned | 2021-06-16T23:56:11Z | - |
| dc.date.available | 2022-08-25 | |
| dc.date.copyright | 2020-08-25 | |
| dc.date.issued | 2020 | |
| dc.date.submitted | 2020-02-17 | |
| dc.identifier.uri | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/65649 | - |
| dc.description.abstract | NO | zh_TW |
| dc.description.abstract | Optoelectronic devices converting light into electricity or vice versa based on quantum mechanical effects of light on electronic semiconductors have a tremendous attraction in modern nanotechnology, which has brought a revolution in the quality of our daily life. In order to eradicate the global challenges such as global warming, fabrication of low cost, low power consumption, wearable, portable, non-toxic, stable, reliable, durable, and environmentally friendly device, the optoelectronic industry demands high-performance optoelectronic semiconducting materials. Though different semiconductors, including nanomaterials, nanowires, and quantum dots, have been utilized for the demonstration of high-performance optoelectronic devices, however, the reported device used complicated fabrication techniques, raising concerns about cost-effectiveness, reliability, reproducibility, and durability. Despite the immense efforts of scientists around the globe over the last decade, progress related to this guideline continues to be insignificant and further improvements are desired. Recently, the hybrid material organometallic nanocomposite, which combines the metal and organic ligand are superior for multiple applications including drug delivery, sensing, and gas storage because of their tunable physiochemical properties and fascinating architectures. These organometallic nanocomposites are also applicable in the fabrication of high-performance optoelectronics owing to the inherent tenability. Such hybrid materials have outstanding photon to electron or electron to photon conversion efficiencies due to fundamental light-matter interactions, good optoelectronic properties, which include a direct and tunable bandgap with high carrier mobility, photoluminescence, and long exciton-lifetime. By utilizing the suitable design technique, the hybrid semiconductor organometallic nanocomposites can be used to fabricate the high-performance unique multifunctional optoelectronic device as compared to their counterparts. Therefore, in order to address the global challenges on the fabrication of high-performance optoelectronic devices, in this research work, we focussed to design, fabricate, and characterize the high-performance multifunctional novel optoelectronic devices include photodetectors, light-emitting diodes, and lasers based on semiconductor organometallic nano-composites. Our investigations are summarized into different sub-topics:
Wearable Photodetector: Trapped Photons Induced Ultrahigh External Quantum Efficiency and Photoresponsivity in Hybrid Graphene/Metal-Organic Framework Broadband Wearable Photodetectors Metal-organic frameworks (MOFs) have recently emerged as attractive materials for their tunable properties, which have been utilized for diverse applications including sensors, gas storage, and drug delivery. However, the high porosity and poor electrical conductivity of MOFs restrict their optoelectronic applications. Owing to the inherent tunability, a broadband photon absorbing MOF can be designed. Combining the superior properties of the MOFs along with ultrahigh carrier mobility of graphene, for the first time, this study reports a highly sensitive, broadband, and wearable photodetector on a polydimethylsiloxane substrate. The external quantum efficiency of the hybrid photodetector is found to be >5 × 108%, which exceeds all the reported values of similar devices. The porosity of the MOF and ripple structure graphene can assist the trapping of photons at the lightharvesting layer. The device photoresponsivity is found to be >106 A W−1 with a response time of <150 ms, which is approximately ten times faster than the current standards of the graphene-organic hybrid photodetectors. In addition, utilizing the excellent flexibility of the graphene layer the wearability of the devices with stretchability up to 100% is demonstrated. The unique discovery of MOF-based high-performance photodetectors opens up a new avenue in organic–inorganic hybrid optoelectronics. Light Emitting Diode (LED): Single-Molecule-Based Electroluminescent Device as Future White Light Source During the last two decades, spectacular development of light-emitting diodes (LEDs) has been achieved owing to their widespread application possibilities. However, traditional LEDs suffer from unavoidable energy loss because of the down conversion of photons, toxicity due to the involvement of rare-earth materials in their production, higher manufacturing cost, and reduced thermal stability that prevent them from all-inclusive applications. To address the existing challenges associated with current commercially available white LEDs, herein, we report a broad-band emission originating from an intrinsic lanthanide-free single-molecule-based LED. Self-assembly of a butterflyshaped strontium-based compound was achieved through the reaction of Sr(NO3)2 with 1,2,3- benzenetricarboxylic acid hydrate (1,2,3-H3btc) under hydrothermal conditions. A white LED based on this single molecule exhibited a remarkable broad-band luminescence spectrum with Commission Internationale de l’Eclairage (CIE) coordinates at (0.33, 0.32) under 30 mA current injection. Such a broad luminescence spectrum can be attributed to the simultaneous existence of several emission lines originating from the intramolecular interactions within the structure. To further examine the nature of the observed transitions, density functional theory (DFT) calculations were carried out to explore the geometric and electronic properties of the complex. Our study thus paves the way toward a key step for developing a basic understanding and the development of high performance broad-band light-emitting devices with environment-friendly characteristics based on organic-inorganic supramolecular materials. Dual Functional Vertical Phototransistor: Graphene Sandwich Stable Perovskite Quantum-Dot Light-Emissive Ultrasensitive and Ultrafast Broadband Vertical Phototransistors Dual-functional devices that can simultaneously detect light and emit light have a tremendous appeal for multiple applications, including displays, sensors, defense, and high-speed optical communication. Despite the tremendous efforts of scientists, the progress of integration of a phototransistor, where the built-in electric field separates the photogenerated excitons, and a light-emitting diode, where the radiative recombination can be enhanced by band offset, into a single device remains a challenge. Combining the superior properties of perovskite quantum dots (PQDs) and graphene, here we report a light-emissive, ultrasensitive, ultrafast, and broadband vertical phototransistor that can simultaneously act as an efficient photodetector and light emitter within a single device. The estimated value of the external quantum efficiency of the vertical phototransistor is ∼1.2 × 1010% with a photoresponsivity of >109 A W−1 and a response time of <50 μs, which exceed all the presently reported vertical phototransistor devices. We also demonstrate that the modulation of the Dirac point of graphene efficiently tunes both amplitude and polarity of the photocurrent. The device exhibits a green emission having a quantum efficiency of 5.6%. The moisture-insensitive and environmentally stable, light-emissive, ultrafast, and ultrasensitive broadband phototransistor creates a useful route for dual-functional optoelectronic devices. Intrinsic Ultra-low Threshold Laser Action from Rationally Molecular Design of Metal-Organic Frameworks Materials Metal-organic frameworks (MOFs) are superior for multiple applications including drug delivery, sensing, and gas storage because of their tunable physiochemical properties and fascinating architectures. Optoelectronics appliance of MOFs is difficult because of porous geometry and conductivity issues. Recently, few optoelectronic devices have been fabricated by suitable design of integrating MOFs with other materials. However, demonstration of laser action arising from MOFs as intrinsic gain media still remains a dream, even though some researches endeavor on encapsulating of luminescence organic laser dyes into the porous skeleton of MOFs to achieve laser action. Unfortunately, the aggregation of such unstable laser dyes causes photoluminescence quenching and energy loss, which limits their practical application. In this research, unprecedently, we demonstrated ultralow threshold (~ 13 nJcm-2) MOFs micro-laser by judicious choice of metal nodes and organic linkers during synthesis of MOFs. We also observed white random lasing from the beautiful micro-flowers of our particularly designed organic linkers. In addition, we showed that the smooth facets of MOFs microcrystals can behave Fabry-Perot resonant cavities having a high quality factor of ~ 103 with excellent photostability. Our unique discovery of stable, non-toxic, high-performance MOFs micro-laser will open up a new route for development of new optoelectronic devices. | en |
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| dc.description.tableofcontents | Table of Content
Chapter 1 : Introduction ……………………………………………….1 1.1 Nanoscience and Nanotechnology……………………………………………........1 1.2 Nanomaterials……………………………………………………………………...2 1.3 Semiconductor Nanomaterials……………………………………………………..3 1.4 Particle Size Quantum Mechanical Confinement…………………………………..4 1.5 Graphene: The First Discovered 2D Material……………………………………...6 1.6 Allotropies of Carbon in Different Dimensions……………………………………6 1.7 Crystal Structure of Graphene……………………………………………………...9 1.8 Electronic Structure of Graphene…………………………………………………10 1.9 The Optical Properties of Graphene………………………………………………11 1.10 Mechanical Properties of Graphene……………………………………………..13 1.11Metal-Organi Frameworks………………………………………………………14 1.12 Organic-Inorganic Hybrid Perovskite…………………………………………...16 1.13 Overview of the Thesis………………………………………………………….20 1.14 References………………………………………………………………………23 Chapter 2 : Theoretical Foundation of Different Optoelectronic Process, Experimental Techniques, and Material Synthesis………...34 2.1 The Light-Matter Interaction……………………………………………………..34 2.2 The Different Photodetection Methods in Graphene-Based Photodetector……….34 2.3. The Principle of Photodetection in Graphene-Based Hybrid Photodetector……...36 2.4 The Advantage of Vertical Phototransistor……………………………………….37 2.5 The Experimental Method of Photodetection……………………………………38 2.6 Optical Spectroscopy……………………………………………………………..39 2.6.1 Photoluminescence Spectroscopy………………………………………………39 2.6.2 Raman Spectroscopy……………………………………………………………42 2.7 Scanning Electron Microscope (SEM)……………………………………………44 2.8 Electroluminescence……………………………………………………………...46 2.9 Random Lasing Action…………………………………………………………...48 2.10 Material Synthesis. ……………………………………………………………...50 2.10.1 Synthesis of Monolayer-graphene by Chemical Vapor Deposition (CVD)……50 2.10.2 Deposition of ZnO by Radio Frequency Sputtering…………………………...53 2.10.3 The Electrodes Deposition by Thermal Evaporation…………………………..54 2.10.4 Synthesis of Metal-Organic framework (MOFs)………………………………55 2.10.5 Synthesis of CH3NH3PbBr3 Perovskite Quantum Dots………………………..56 2.11 References………………………………………………………………………57 Chapter 3 : Trapped Photons Induced Ultrahigh External Quantum Efficiency and Photoresponsivity in Hybrid Graphene/Metal-Organic Framework Broadband Wearable Photodetectors…………………..62 3.1 Introduction………………………………………………………………………62 3.2 Results and Discussion……………………………………………………………65 3.2.1 Structure and Characteristics of Component Materials…………………………65 3.2.2 The MOF-Graphene Composite Photodetector and its Operational Principle......67 3.2.3 Responsivity, Detectivity, Gain and Quantum Efficiency of the Device..............70 3.2.4 Broadband Frequency Detection of the Device....................................................77 3.2.5 Strain-Dependent Study.......................................................................................79 3.2.6 Device Flexibility................................................................................................81 3.2.7 Device Durability and Stability…………………………………………………83 3.3 Conclusions............................................................................................................84 3.4 Experimental Section..............................................................................................86 3.5 References..............................................................................................................90 Chapter 4 : Single-Molecule Based Electroluminescent Device as Future White Light Source…………………………………………….99 4.1 Introduction………………………………………………………………………99 4.2. Results and Discussion………………………………………………………….101 4.2.1 Self-assembly of Sr-based Supramolecular Compound 1 ……………………..101 4.2.2 Crystal Structure of Sr-based Supramolecular Compound 1 ………………….101 4.2.3 Photoluminescence Properties of Sr-based Supramolecular Compound 1 ……103 4.2.4 Photo and Electrochemical Stability of Material……………………………...106 4.2.5 Electronic Band Structures of Compound 1.......................................................108 4.2.6 Electroluminescent Device based on Single-Molecular Crystalline Assembly of Compound 1………………………………………………………………………...110 4.2.7 Device Performance, Quantum Efficiency and Stability………………………114 4.3 Conclusions……………………………………………………………………..115 4.4 Experimental Section……………………………………………………………116 4.5 References………………………………………………………………………121 Chapter 5 : Graphene Sandwich Stable Perovskite Quantum-Dots Light Emissive Ultrasensitive and Ultrafast Broadband Vertical Phototransistors………………………………………………………127 5.1 Introduction……………………………………………………………………..127 5.2 Results and Discussion…………………………………………………………..130 5.2.1 Synthesis, Structural, Microstructural and Characteristic Analysis of Component Materials…………………………………………………………………………….130 5.2.2 Optical Properties……………………………………………………………..132 5.2.3 Graphene-PQDs-Graphene Vertical Phototransistor and Its Principle of Operation....................................................................................................................135 5.2.4 Photoresponse Performance of Phototransistor..................................................138 5.2.5 Gate Tunable Photocurrent................................................................................143 5.2.6 Broadband Photodetection of the Device...........................................................145 5.2.7 Electroluminescence Study of Vertical Photodetector.......................................146 5.2.8 Device Performance and Stability……………………………………………..148 5.3 Conclusions..........................................................................................................149 5.4 Experimental Section............................................................................................150 5.5 References............................................................................................................153 Chapter 6 : Intrinsic Ultra-low Threshold Laser Action from Rationally Molecular Design of Metal-Organic Frameworks Materials………………………………………………………………162 6.1 Introduction……………………………………………………………………..162 6.2 Results and Discussion…………………………………………………………..164 6.2.1 Synthesis of Single-crystalline Sr-Based MOF Compound…………………...164 6.2.2 Structural Study of Sr-Based MOF Compound………………………………..165 6.2.3 Thermal and Optical Stability of MOF Compound…………………………...168 6.2.4 The Calculation of Electronic Band Structure by Density Functional Theory....170 6.2.5 White Random Laser from Microflowers of Organic Linkers ………………...172 6.2.6 Random Laser from MOFs................................................................................177 6.3 Conclusions..........................................................................................................182 6.4 Experimental Method...........................................................................................183 6.5 References............................................................................................................185 Chapter 7 : Conclusion & Future Perspective……………………....190 7.1 Conclusions……………………………………………………………………..190 7.2 Future Perspective.................................................................................................195 List of Figures Figure 1.1. Features of a nanomaterial at different dimensions with the plot of the density of states vs energy. …………………………………………………………….3 Figure 1.2. Features of graphite in different nanodimension. 2D graphene sheet can be stacked into 3D to form graphite, rolled into 1D to form carbon nanotubes (CNT), and wrapped up into 0D to form fullerene. …………………………………………………8 Figure 1.3. Crystal structure of graphene. (a) Triangular Bravais lattice of graphene. (b) First Brillouin zone of the crystal structure of graphene. …………………………...9 Figure 1.4. The electronic structure of graphene. (a) Schematic of electron transition according to tight-binding Hamiltonian. (b) Dirac points of the single-layer graphene corresponding to linear dispersion relation. ………………………………………….11 Figure 1.5. Schematic for demonstration of Klein paradox in graphene. ……………12 Figure 1.6. Schematic of graphene hanger. …………………………………………..13 Figure 1.7. Schematic of graphene ripple structure. …………………………………14 Figure 1.8. (a) Structure of the metal-organic frameworks (MOFs). (b) Schematic representation of the different light-emission mechanism of MOFs. …………………16 Figure 1.9. Structure of 2D RPPs of (BA)2(MA)n-1PbnI3n+1. The n indicates the number of inorganic octahedral layers present in the perovskite unit cell. For 2D layered perovskite n = 1,2,3, and etc. and n = ∞ represents the bulk 3D perovskite. …………..18 Figure 2.1. Schematic of the energy band diagram representing the principle of photodetection for graphene-based hybrid photodetector. …………………………36 Figure 2.2. Experimental setup of photodetection experiment. (a) Image of different source meter used for photodetection study. (b) Image of the optical microscope and other instruments used in photoresponse measurement. (c) Image of microprobes connected with the electrodes of the photodetector device. …………………………39 Figure 2.3. The working principle of photoluminescence instrument. ……………….40 Figure 2.4. (a) Photograph of the micro-photoluminescence instrument used for the investigation of PL spectra. (b) Photograph of Horiba Jobin Yvon iHR 550 spectrometer………………………………………………………………………….41 Figure 2.5. (a) Different Raman scattering spectrum. (b) Basic principle of operation of the Raman spectroscopy Instrument. A photograph of the Raman instrument used for Raman spectra study. ……………………………………………………………..43 Figure 2.6. (a) Schematic of the different components an SEM instrument. (b) Photograph of our SEM instrument used for imaging of the different nanomaterials and optoelectronic devices. (c) Photograph of HRTEM machine used for imaging the perovskite quantum dots. …………………………………………………………….45 Figure 2.7. Working principle of light emitting diode (LED). ………………………46 Figure 2.8. Schematic for demonstration of random lasing. …………………………50 Figure 2.9. Photograph of CVD machine used for the synthesis of the single-layer graphene. ……………………………………………………………………………..51 Figure 2.10. Schematic of the experimental set-up for electrolysis. …………………52 Figure 2.11. Schematic of the working principle of a sputtering technique. …………53 Figure 2.12. (a) Photograph of RF sputtering machine used for the deposition of ZnO. (b) Photograph of thermal evaporation machine used for deposition of electrode materials. ……………………………………………………………………………..55 Figure 3.1. (a) MOF structure. The ligand forms a bridge between two metallic layers to form the supramolecular composite. (b) Simulated and experimental PXRD data for MOF compound 1 under different temperature. (c) UV-Vis absorption spectra of MOF compound 1. (d) Photoluminescence spectra of the MOF sample at a pump flounce of 38 μW under the illumination of 266 nm laser………………………………………..66 Figure 3.2. (a) Schematic diagram of the photodetector. (b) SEM image of ripple structure. (c) Transient photoresponse of the device current under the illumination by 325 nm laser with 10 nW of power at the bias voltage of 0.1 V. (d) Energy band diagram of the graphene-MOF hybrid photodetector before and after the illumination of photons and applying an external bias. ......................................................................................68 Figure 3.3. The device performance. (a) Photocurrent-voltage characteristics of graphene/MOF under the illumination of the different power by 325 nm laser. (b) The power dependence of the transient photocurrent response under bias voltage VSD = 0.1 V. (c) Variation of photoresponsivity as a function of illumination power. (d) Schematic of multiple reflections process of an incident photon inside the ripple structure. ..........71 Figure 3.4. Response time and photocurrent gain of the device. (a) Response time, while the laser is turned ON, under light illumination of power 10 nW. (b) Response time, while the laser is turned OFF, under light illumination of power 10 nW. (c) Photocurrent gain as a function of the illumination power. The red spheres resemblance the experimental data, while the solid blue curve is the theoretical plot with the best fitting of the experimental data. ....................................................................................74 Figure 3.5. Broadband photodetection from UV to the visible regime of illuminating photons. (a) Temporal photoresponse curve under 325 nm, 457 nm, 535 nm, and 656 nm wavelength laser illuminations at bias voltage VSD = 0.1 V. (b) Comparison of excitation wavelength dependent photoresponsivity with absorption spectra. (c) Time-resolved photoluminescence (TRPL) spectra at different peak positions in the PL spectrum. ......................................................................................................................78 Figure 3.6. The stretchability of the device: the application of tensile strains. (a) Dynamic photoresponse under the application of different strains at bias voltage 0.1 V and the illumination of 10 nW laser power using of 325 nm laser. (b) Photocurrent gain of the device under different applied strain. (c) Dark conductivity ratio of the device under different strains. The blue line is drawn to guide the eyes. (d) The stability of the device under the application of repeated strain of 75% and releasing it back to the 0% strain. ...........................................................................................................................80 Figure 3.7. Device flexibility: application of bending strain. (a) Schematic illustration of the device under bending strain. (b) Dynamic photoresponse of the device under the application of different bending strains at bias voltage 0.1 V and the illumination of 10 nW laser power using of 325 nm laser. (c) Obtained photocurrent of the device under different bending strains. (d) Obtained photocurrent the device under repeated application of the bending strain of 1 cm diameter and releasing it back to the flat condition.......................................................................................................................82 Figure 3.8. Stability of the device performance, the photocurrent of the device, measured over a long period of time. ............................................................................84 Figure 3.9. Schematic illustration of the different steps of the device fabrication process. (i) PDMS put on the top of the glass plate. (ii) PDMS was stretched and clamped with glass plate by using clips. (iii) Monolayer graphene grown by CVD was transferred on the top of the stretched PDMS. (iv) 100 nm Au electrodes were deposited by a thermal evaporation technique after putting the mask on the top of the graphene. (v) MOF was spin coated on the top of the graphene. (vi) Finally, the clips were carefully released to produce the regular rippled structure. ...........................................................................88 Figure 4.1. (a) Compound 1 is connected in an ABAB fashion in the c-axis, which is extended into 2D sheets. (b) The weak parallel displaced parallel-displaced π-stacking interactions in between the neighbouring supramolecular arrays in compound 1. (c) Hydrogen-bonding interactions (O10-H10E···O3 = 1.892 Å; O10-H10D···O4 = 1.863 Å; (O2-H2···O10 = 1.811 Å; O6-H6···O10 = 1.850 Å; O9-H9B···O8 = 2.262 Å; O8-H8···O4 = 2.215~2.616 Å) are shown in between the four neighbouring supramolecular units.………………………………………………………………………………102 Figure 4.2. (a) Photoluminescence spectra of compound 1 at variable laser power under illumination by a 266 nm pulsed laser. (b) CIE chromaticity diagram highlighting corresponding chromaticity coordinates of compound 1. The CIE coordinate corresponding to the emission was found to be (0.19, 0.25). The inset is a picture taken by a mobile camera while the material is exposed to 266 nm laser during the PL measurements. (c) Photoluminescence spectrum of organic molecule (benzene-1,2,3-tricarboxylic acid hydrate). (d) Time Resolved Photo luminescence (TRPL) measurement: TRPL decay curve at different peak positions of PL spectra under 374 nm laser illumination. …............................................................................................104 Figure 4.3. (a) A schematic of the device for electrochemical study, (b) current–voltage characteristic of compound 1 at ambient conditions before and after the application of a constant voltage (20 V) for 8 hours, (c) photoluminescent spectra and (d) Raman spectra of the compound under the same experimental conditions, respectively. ………………………………………………………………………...107 Figure 4.4. (a) Optimized periodic structure of compound 1 with solvent molecules and energy band structure for HOMO-LUMO states of compound 1 with solvent molecules (solvent molecules highlighted), (b) optimized periodic structure of compound 1 without solvent molecules and energy bands structure for HOMO-LUMO states of compound 1 without solvent molecules. (Magenta: strontium; red: oxygen; dark gray: carbon; light gray: hydrogen). ……………………………………………………....109 Figure 4.5. (a) Schematic illustration of visible broadband LED device, where the p-n junction is formed by 155.5 nm ZnO and Sr-compound on the top of the Ag 199.6 nm film. p-type Si/SiO2 and ITO were used as the substrate and the top electrode, respectively. (b) Optical photo of light emission from device taken by mobile camera. (c) Electroluminescence (EL) spectrum of Sr-compound based LED device. (d) Scanning electron microscopic image of the solid-state light emitting device (cross sectional view). e) Energy band diagram for the constituent materials of the device showing different transitions during carrier injections………………………………111 Figure 4.6. (a) EL spectra of the device under a forward injection current of 20 mA and 30 mA. (b) Stability of the device performance over time. ………………………….113 Figure 5.1. Structural and microstructural studies of PQDs. (a) Schematic representation of organic-inorganic hybrid perovskite with MBr6 octahedra drawn by using VESTA with CIF file corresponds to the JCPDS file no mp-977012 for CH3NH3PbBr3. (b) The experimental XRD patterns at room temperature (red line) with the theoretical simulated curve (blue line) by Rietveld refinement using the same CIF file. (c) HRTEM micrograph of an isolated perovskite nanoparticle. (d) HRTEM image of the crystalline lattice plane (221) has an interplanar distance ~ 2.2 Å corresponding to lattice plane (221) and corresponding FFT (Fast Fourier Transform) arrangement. HRTEM analysis reveals clear-cut lattice spacing and FFT arrangement have explicit spots, which are consistent with the CH3NH3PbBr3 bulk. …………………………..131 Figure 5.2. Optical study of PQDs. (a) Photoluminescence spectrum of PQDs at a laser power of 26 µJ under excitation from 374 nm laser. The inset picture shows the mobile camera image of light emission from PQDs during the PL measurements. (b) The TRPL spectrum at different emission wavelengths in the PL spectrum. (c) UV-Vis absorption spectrum of PQDs compound. Inset indicates a zoomed view of the absorption spectrum. (d) Raman spectrum of the compound under the excitation by a 532 nm laser. ..........134 Figure 5.3. Graphene/PQDs/graphene vertical phototransistor. (a) Schematic design of vertical phototransistor. (b) The corresponding SEM micrograph of fabricated phototransistor. (c) I-V curve under dark (blue line) and 325 nm laser irradiation (red line) with laser power density 0.3 µWcm-2. (d) Energy band representation of the graphene/PQDs/graphene vertical phototransistor under the excitation of photons and applying an external bias. ...........................................................................................137 Figure 5.4. The photoresponse performance of the device. (a) The temporal photoresponse of the vertical phototransistor under 457 nm laser irradiation having laser power 10 nW with a spot size of radius 1mm at the bias voltage of 2V. (b) Current-voltage curves of the phototransistor under the excitation of the diverse light-power by 457 nm laser. (c) The variation of temporal photocurrent with the power of illumination light. (d) The illumination light-power dependent photoresponsivity curve of the phototransistor. ..........................................................................................................139 Figure 5.5. Photoresponse-time and quantum efficiency of vertical phototransistor. (a) Photoresponse-time, while the 457 nm laser is OFF condition. (b) Photoresponse-time, while the 457 nm laser is ON condition. (c) Variation of EQE with excitation light power. (d) The variation of photocurrent gain with excitation light power. The blue spheres indicate the experimentally observed data, while the red curve represents the theoretically simulated plot. There is good agreement between theoretical simulation and experimental observation. ...................................................................................141 Figure 5.6. Gate voltage tunable photocurrent of the vertical phototransistor device. (a) The ID vs VD curve measured at + 40 V gate voltage. The two crimps because of the Dirac point of top graphene (red cursor) and bottom graphene (green cursor). (b) The current-voltage (ID-VD) curves obtained in the dark (black curve), under 532 nm laser irradiation (green curve), and an application of - 10 V gate voltage with laser irradiation, respectively. (c) The current-voltage (ID-VD) curves obtained under 532 nm laser irradiation (black curve) and an application of + 10 V gate voltage with laser irradiation (red curve), respectively. (d) A series of ID-VD plots with increasing positive gate voltage………………………………………………………………………………144 Figure 5.7. Broadband photoresponse of phototransistor. (a) Transient photoresponse curve by the excitation from various laser sources ranging from UV-IR range at bias voltage VSD = 2V. (b) Comparison of observed absorption spectrum with illumination-wavelength dependent photoresponsivity...................................................................146 Figure 5.8. Demonstration of the electroluminescence of the vertical phototransistor device. (a) EL spectrum of phototransistor under different bias currents. Inset shows an image of light emission from the device by using a mobile camera. (b) CIE diagram of light emissions measured at an injection current 30 mA. The circle with CIE coordinates (0.27, 0.50) indicates the green emission as observed in PL study. (c) Energy band diagram for light emission. (d) The durability of the device performance in both the photocurrent and electroluminescence, measured at an ambient condition over an extended period of time. .............................................................................................147 Figure 5.9. Schematic description of the fabrication process of light-emissive phototransistor. ..........................................................................................................151 Figure 6.1. (a) Asymmetric unit of MOFs compound. (b) Coordination model of organic ndc2- ligand. (c) A layered structure connected through pillar ligands and the arrangement of the one dimensional inorganic chain by edge-sharing forms pentagonal prisms. (d) The three dimensional structural view of MOFs along b-axis...................166 Figure 6.2. The optical stability of MOFs compound. (a) Schematic for the investigation of electro-optical stability of MOFs compound. (b) Raman spectra of MOFs compound under the application of a constant electric field under ambient condition. (c) Photoluminescence spectra of MOFs under excitation by a 374 nm laser having power density 10 nJcm-2 before and after the application of a constant electric field 150 Vcm-1. The photoluminescence spectrum of free ligand under the same experimental conditions. Inset shows the photograph of light emission taken by using mobile camera under the illumination of laser on the MOFs (green) and organic ligand (white). ……………………………………………………………………………...169 Figure 6.3. (a) Band structure, (b) Total DOS (green area) and PDOS (other color). The dashed line representing the Fermi level. The orbital feature of the (c) VBM and (d) CBM, respectively. Here, the black box illustrates the periodic unit cell. ...................171 Figure 6.4. White random lasing of organic linker. (a) SEM micrograph of organic linker micro-flowers over a large area (b) SEM image of the single micro-flowers. (c) The enlarged view of the porous nest like network inside a micro-flower. (d) The optical pumping energy density-dependent white random lasing spectra by excitation of 374 nm laser. …………………………………………………………………………….173 Figure 6.5. (a) Variation of FWHM and emission intensity versus the optical pumping energy density for the pure organic linker. (b) The TRPL spectra of the pure organic linker under different excitation energy density. (c) Pumping energy density dependence of excited state carrier lifetime of organic ligand. (d) Angular dependence of the lasing spectra………………………………………………………………….175 Figure 6.6. Angular dependence of the lasing spectra recorded at pump energy density of 60 nJcm-2 by using a 374 nm laser source…………………………………………176 Figure 6.7. Random laser action for MOFs compound. (a) SEM micrograph of synthesized MOFs nano-cubes with smooth facets. (b) The optical pumping energy density dependent random laser spectra of MOFs nano-cubes. (c) The variation of FWHM and emission intensity of MOFs random laser versus optical pumping energy density. (d) The TRPL spectra of MOFs nano-cubes under different excitation energy density. ……………………………………………………………………………...178 Figure 6.8. Angular dependence of the lasing spectra of MOFs compound recorded at pump energy density of 35 nJ/cm2 by using a 374 nm laser source. …………………179 Figure 6.9. Fabry-Parot features of MOFs microcrystals. The lasing spectra of microcrystals having different size under the pump fluence from 374 nm laser with pumping power density 56 nJcm-2. Bottom shows the optical microscope image of MOFs microcrystal corresponding to each lasing spectrum. ………………………..180 Figure 6.10. (a) The variation of optical mode spacing with the size of MOFs microcrystal. (b) The electric field distribution of optical mode observed in FDTD simulation. The electric field distribution study indicates the confinement of photons within the MOFs microcrystal. ...................................................................................181 List of Tables Table 3.1 : The photoluminescence carrier lifetime of MOF Compound...................79 Table 4.1 : The photoluminescence carrier lifetime of compound 1 and the ligand....106 Table 4.2 : Crystal and structure refinement data for compound 1………………….118 Table 6.1 : Crystal data and structure refinement for CCDC number1950187...........167 | |
| dc.language.iso | en | |
| dc.subject | NO | zh_TW |
| dc.subject | GRAPHENE | en |
| dc.subject | ORGANOMETALLIC COMPOUND | en |
| dc.subject | PHOTODETECTOR | en |
| dc.subject | PHOTOTRANSISTOR | en |
| dc.subject | LED | en |
| dc.subject | LASER | en |
| dc.title | 基於有機金屬納米複合材料的半導體光電元件之研究與應用 | zh_TW |
| dc.title | High-Performance Photodetectors, Light Emitting Diodes, and Lasers Based on Organometallic Compounds | en |
| dc.type | Thesis | |
| dc.date.schoolyear | 108-2 | |
| dc.description.degree | 博士 | |
| dc.contributor.oralexamcommittee | 張嘉升(Chia-Seng Chang),陳啟東(Chii-Dong Chen),朱治偉(Chih-Wei Chu),王偉華(Wei-Hua Wang),謝馬利歐(Mario-Hofmann) | |
| dc.subject.keyword | NO, | zh_TW |
| dc.subject.keyword | GRAPHENE,ORGANOMETALLIC COMPOUND,PHOTODETECTOR,PHOTOTRANSISTOR,LED,LASER, | en |
| dc.relation.page | 197 | |
| dc.identifier.doi | 10.6342/NTU202000459 | |
| dc.rights.note | 有償授權 | |
| dc.date.accepted | 2020-02-17 | |
| dc.contributor.author-college | 理學院 | zh_TW |
| dc.contributor.author-dept | 物理學研究所 | zh_TW |
| 顯示於系所單位： | 物理學系 | |
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