MEMS and Nanotechnology ClearinghouseMIT - Organic, Molecular and Nanostructured Electronics - Physics and Technology2008-06-09 - 2008-06-13MIT Campus | Cambridge, MA http://web.mit.edu/mitpep/pi/courses/organic_electronics.html Over the last decade, enormous strides have been made in the field of organic electronics. A first generation of visible organic light emitting devices has been commercialized. Optically pumped lasers have been demonstrated at UV, visible, and IR wavelengths. Photodetectors with collection efficiencies as high as 75%, and solar cells with power conversion efficiencies as high as 3% have been reported. Printed organic thin film transistor circuits containing hundreds of active gates have been operated at frequencies exceeding 1 kHz. As a whole, this work represents an extraordinary technological achievement on an entirely new materials platform, but it is just a beginning of what is to come. With the advent of techniques for manipulating materials at the nanoscale and development of manufacturing methods for devising large area nanostructures, further advancements are envisioned. This course will review basic concepts underlying the design, fabrication, and operation of three dominant types of organic electronic devices: light emitting devices (OLEDs), photosensitive devices (solar cells and photodetectors), and field effect transistors (OFETs). We will also discuss, but devote less time to, organic lasers, organic memories, and chemical sensors. The course aims to present a broad and practical survey of the field and to immerse you in the broad field of organic materials. As a sub-class of nanostructured solids, organic thin films exemplify challenges of the practical nanotechnologies. Many concepts presented in the class are directly transferable to a broader field of nanostructured materials. The course begins with an overview of organic semiconductors, their structures, general physical and electronic properties. Electronic structure of a single organic molecule will be used as a guide to the electronic behavior of organic aggregate structures. A brief discussion of methods for forming organic thin film structures will set the stage for the detailed discussion of active devices. In describing organic photosensitive devices we will first introduce the concept of an exciton, the molecular or aggregate unit excitation that fundamentally governs the operation of all organic optoelectronic devices. The effects of exciton diffusion, dissociation, and luminescence will be examined in the photogeneration process in an organic heterojunction photovoltaic cell, and an organic multilayer photodetector. Description of start-up company efforts to commercialize organic electrochemical cells and inorganic-nanorod/polymer-organic composite cells will conclude this section of the course. The course center stage will be given to organic light emitting device technologies. We will start by reviewing human perception of color as the guide to the design of all display technologies. Through historical review we will introduce the basic OLED structure and operating characteristics. These will then be used as a platform to examine charge carrier transport in organic thin films and carrier injection at electrode/organic interfaces. Discussion will lead us through the description of transparent, inverted, and flexible OLEDs, TOLEDs, OILEDs, and FOLEDs, respectively. The electrophosphorescence process will be highlighted as the culprit for today's record efficiencies in doped phosphorescent OLED structures (PH-OLEDs). Advanced concepts of light guiding in OLEDs, microcavity effects, solid state solvation, and exciton dynamics in disordered organic films will only be alluded to for their technological significance. Description of the electronic driving schemes for OLED displays will motivate discussion of manufacturing methods for full color display panels including evaporative deposition and printing schemes. As the above discussion will primarily focus on molecular OLEDs, this section will conclude by highlighting physical and manufacturing differences in polymer LED technology and the emerging technology of quantum dot LEDs (QD LEDs) that hybridize organic materials with inorganic nanocrystal quantum dots. In the organic FET section of the course, we will describe device structure and operation. Emphasis will be placed on understanding basic device physics including: the critical field effect process by which the conductance of the device is "gated"; the two major regimes of FET operation (linear and saturation); the elementary current-voltage equations and the extraction of important device parameters such as charge mobility, on-to-off ratio, threshold voltage and sub-threshold slope. State-of-the-art accomplishments in circuit design for organic electronics will also be highlighted. Throughout the course, the themes which will permeate all device discussions are the microstructure of the semiconductor films, the physical origin of the relevant optical and electronic processes, uniqueness of the organic material set and its potential to change manufacturing paradigms in 21st century electronics. HANDS-ON LABORATORY Additional Nano & Micro Technology / Tribology related short courses at MIT
For more information: http://web.mit.edu/mitpep/pi/courses/organic_electronics.html |