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

Abstract

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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.