Low Threshold Organic Semiconductor Lasers

This thesis focuses on two areas - the development of miniature plastic lasers that can be powered by LEDs, and the application of these lasers as highly sensitive sensors for vapours of nitroaromatic explosives (e.g. TNT). Polymer lasers are extremely compact visible lasers; the research described in the thesis is groundbreaking, driving forward the technology and physical understanding to allow these lasers to be routinely pumped by a single high-power LED. A notable advance in the work is the demonstration of nanoimprinted polymer lasers, which exhibit the world's lowest pump threshold densities by two orders of magnitude. The thesis also advances the application of these compact, novel lasers as highly sensitive detectors of explosive vapours, demonstrating that rapid detection can be achieved when microporous polymers are used. This work also demonstrates a prototype CMOS-based microsystem sensor for explosive vapours, exploiting a new detection approach.

Organic lasers are broadly tunable coherent sources, potentially compact, convenient and manufactured at low-costs. Appeared in the mid 60’s as solid-state alternatives for liquid dye lasers, they recently gained a new dimension after the demonstration of organic semiconductor lasers in the 90's. More recently, new perspectives appeared at the nanoscale, with organic polariton and surface plasmon lasers. After a brief reminder to laser physics, a first chapter exposes what makes organic solid-state organic lasers specific. The laser architectures used in organic lasers are then reviewed, with a state-of-the-art review of the performances of devices with regard to output power, threshold, lifetime, beam quality etc. A survey of the recent trends in the field is given, highlighting the latest developments with a special focus on the challenges remaining for achieving direct electrical pumping of organic semiconductor lasers. A last chapter covers the applications of organic solid-state lasers.

This high-class book reflects a decade of intense research, culminating in excellent successes over the last few years. The contributions from both academia as well as the industry leaders combine the fundamentals and latest research results with application know-how and examples of functioning displays. As a result, all the four important aspects of OLEDs are covered: - syntheses of the organic materials - physical theory of electroluminescence and device efficiency - device conception and construction - characterization of both materials and devices. The whole is naturally rounded off with a look at what the future holds in store. The editor, Klaus Muellen, is director of the highly prestigious MPI for polymer research in Mainz, Germany, while the authors include Nobel Laureate Alan Heeger, one of the most notable founders of the field, Richard Friend, as well as Ching Tang, Eastman Kodak's number-one OLED researcher, known throughout the entire community for his key publications.

In the past 30 years, organic conjugated molecules have received a lot of attention in research because of their unique combination of active properties typical of semiconductors and the technological appeal typical of plastic materials. Among the different applications proposed for organic materials, organic lasers are quickly approaching the performance required in real devices, while research on novel active materials is still ongoing. The book covers the basic aspects of the measurement techniques of optical gain and amplified spontaneous emission (ASE) in organic films as well as the photophysics of organic materials that can be understood using ASE measurements. It reviews the recent advances in the development of new active materials for organic lasers as well as the actual state of the art of scattering-assisted random lasers and of strongly coupled organic microcavities, both promising interesting developments in the near future. Finally, it gives a detailed review of the state of the art of the organic lasers actually closest to real applications, namely external cavity lasers and distributed feedback lasers. The book is unique that it covers basic aspects, technological aspects, and systems, which are still a subject of basic science research.

This book comprehensively describes organic electronic devices developed in the past decades. It not only covers the mainstream devices including organic light emitting diodes (OLEDs), organic photovoltaics (OPVs), and organic thin-film transistors (OTFTs) but also includes devices of recent interest such as organic immune transistors, organic photocatalysis devices, and themoelectrical devices. The book starts from the introduction of basic theory of organic semiconductor materials and devices, which acquaints the readers with the concepts of each type of device described in the following chapters. It also discusses the working principles, device layout, and fabrication process of these devices. The book is intended for undergraduate and postgraduate students who are interested in organic electronics, researchers/engineers working in the field of organic electronic devices/systems.

Organic dye laser stands a chance to become the next generation of the light source. It is very interesting because organic dyes can cover a wide range of the pectrum of visible light. To realise organic solid-state laser, several organic dyes can be doped in a polymer matrix. One of the examples of low-priced polymer is poly(methyl methacrylate) (PMMA). However, the study of PMMA as a polymer matrix for organic dyes as a thin-film laser was not extensive. This thesis focused on the feasibility of organic dye-doped PMMA as a thin-film laser.