The ECE Herald Volume 2 Issue 6
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NIT ANDHRA PRADESH VOLUME 2 ISSUE 6 The Official ECE Newsletter Issue date: 5th January, 2020 “Wishing you 12 months of success, 52 weeks of laughter, 365 days of fun, 8760 hours of joy, 525600 minutes of good luck and 31536000 seconds of happiness” ORGANIC LIGHT-EMITTING DIODES interactions which are called excitons. Recombination of an electron and hole from an exciton cause the emission of electromagnetic radiation and in this way, - P. Shilpa (611867) Organic light-emitting diodes (OLEDs) are solid-state light sources made of the molecule energetically turns back to its ground state as the last step. organic semiconductor (OSC) materials. Various functional materials help to The emitted photon wavelength then depends on the material. For example, facilitate the conversion of injected charges into emitted photons at the with AlQ3 green light around 520 nm is emitted. OLED devices fabricated for maximum possible efficiency and further are assembled specifically to realize large screens must provide three main colours (RGB—red green blue). On the the desired emitted colour—be it monochrome or broadband emissions for other hand, lighting studies for industrial applications focused on white colour displays or solid-state lighting (SSL), respectively. The materials used can be organic LEDs. Usually, white light can be obtained from the mixture of two or both small molecules (Tang and VanSlyke, 1987) and polymers (Burroughes et three main colours and that means we need to use at least two chromophoric al., 1990), where any possible combination of the two material classes best materials as the emission layer on the same device. meets the requirements with respect to desired applications and most suitable Organic Small Molecules and Polymers Semiconductor Material for OLED processability. With few exceptions, the organic materials can be made and Applications: upscaled at low cost, and their processing schemes suggest truly economic mass Material scientists production. For the first applications entering the market (i.e., small displays for have developed a handheld devices like smartphones and tablets), the production of such panels is large number of small already profitable. molecules used in OLED technology. Some representative small molecules used in OLED. White Organic Light-emitting Diodes: An organic light-emitting diode (OLED) is an electroluminescent light source that consists of an emissive semiconducting layer or layer stack, formed by organic molecules, sandwiched in between a pair of electrode layers. At least one of the electrode layers is optically transparent. When a direct current is passed through the device, light is emitted as a result of recombination of electrons and holes that are injected from the cathode and anode, respectively. Depending on the organic layer composition, the emission can be chosen either to be confined to a relatively narrow band in the optical spectrum, leading to a Working Mechanism of OLED: monochrome OLED or to be distributed over the entire visible part of the In a simple organic LED, whole device architectures can be fabricated by electromagnetic spectrum, leading to a white OLED. White OLEDs are studied solution process or thermal evaporation techniques. Although small molecules intensively for applications in lighting and displays. Displays based on white can be deposited by both of these methods, conjugated polymers can be OLED pixels that are covered with red, green, and blue colour filtering layers deposited only by solution process methods. The working steps of an are already commercially available, forming an alternative to OLED displays in electroluminescent device can be explained in a few steps. As a first step, charge which the pixels are based on different (red, green, and blue-emitting) organic carriers (electrons and holes) are injected from electrodes under an applied semiconductors. In liquid crystal displays, white OLEDs can serve as a electrical potential to the transport layer. These transport layers also act as backlight. blocking layers of the opposite charge types. In the emission layer (inside the REFERENCES luminescent material) electrons and holes can be captured by coulombs • R. Coehoorn, H. Boerner, in Encyclopedia of Materials: Science and Technology. CONVOCATION 2019 • Shreya Kudari (EEE) - Institute and Branch 3. MOTHER TONGUE: He said, “Learn any Gold Medal language. But remember that any foreign -Mohan (611775) • Veramallu Jhanakeerti Priya (ECE) language is regarded as glasses to our Mother • Thota Devika (Bio-tech) tongue which is regarded as eyesight. Without • Kandavalli Himanandini (Chemical) eyesight even the costliest glasses are useless. • K. Jayashankar Reddy (CSE) So never forget our Mother tongue”. • Sriram Lakshmi Manasa (Civil) 4. JANMABHUMI. He said “Do something for • Msk Hemanth (Mechanical) the benefit of your birthplace”. • Aditya Bharadwaj (MME) 5. ALMA MATER. “No one should forget their Out of 379 students in the first batch, 275 Teachers. Every graduand should contribute to students attended and received their degree from the development of their college.” Our institute's first Convocation was held on 24-12- Honourable Director of NIT Andhra, Dr.CSP Rao. He suggested various areas where technological 19 at the permanent campus. Our Vice President Our Honourable State Governor Biswabhusan advancement is needed like Weather forecast, Solar Muppavarapu Venkaiah Naidu along with Andhra Harichandan advised students that they shouldn’t energy, Water management, new methods to recycle Pradesh State Governor Biswabhusan Harichandan, fail in performing their fundamental duties as waste materials, Agriculture Market management IIT Tirupati director Professor K.N. Satyanarayana citizens of India and also advised all the Graduands and developing new methods for implementing attended the convocation as Chief guests. West not to be complacent with what they have achieved Government Schemes through online portals. Godavari Collector Revu Mutyala Raju, Ex MLA till date and not to stop until their dreams are IIT Tirupati director Dr. K.N. Satyanarayana Pydikondala Manikyala Rao, State Cabinet achieved. appreciated SHIRKE company for their effort in Ministers Taneti Vanitha, Sri Ranganatha Raju and The main attraction of the event, Honourable Vice completing the construction in such a short time. He MP Raghu Rama Krishna Raju and Tadepalligudem President of India, Venkaiah Naidu gave a thought- suggested that the graduands shouldn’t forget about MLA Kottu Satyanarayana attended the provoking speech. He advised the graduands not to their college and should contribute to the Convocation along with chief guests. forget about five things: development of the college. 1. PARENTS After IIT director’s speech, Our director distributed Gold Medals (8 individual Branch toppers and an 2. MOTHERLAND: He advised students who degrees to Graduands. With a vote of thanks to the Institute Gold Medal) were awarded by Vice wished to study in foreign countries, “GO. chief guests, the dignitaries, the Graduands and their President Venkaiah Naidu to the following students: LEARN. EARN. RETURN” to serve the parents, the first convocation of our NIT was motherland. brought to an end. PAGE 1 GATE PROBLEMS Electromagnetic interference -Sourav(611785) 1. For a Super heterodyne receiver, the intermediate Before knowing about EMI filter, frequency is 15 MHz and the local oscillator frequency first we need to know what EMI is. is 3.5GHz. If the frequency of the received signal is Electromagnetic interference (EMI), greater than the local oscillator frequency , then the occurs when an electronic device is image frequency (in MHz) is ____ affected or interrupted by unwanted signals (noise) that are generated either by its own internal integrated 2. A Device with input x(t) and output y(t) is characterized electronic devices (intra EMI) or by by y(t) = x2 t . An FM signal with frequency deviation other surrounding external of 90KHz and modulating signal of bandwidth of 5KHz electronic devices (inter EMI). This is applied to this device. The Bandwidth of output signal effect of interrupting the intended is currents of the devices by the A. 370 KHz unwanted disruptive currents can also be called as electromagnetic B. 190 KHz noise. Depending on the severity of the disruption, EMI may impact the quality of C. 380 KHz the signal the device receives, may cause a component to fail or malfunction D. 95 KHz temporarily or permanently damage the electronic device. EMI can also be categorized in many ways based on the duration of the signal, band width and also **Solutions to the previous issue questions are included in the e-copy by the source which generates the EMI, the interference can be continuous or sporadic. Sporadic EMI occurs when the source is lightning which causes temporary interruptions. Basically EMI is of two types, radiated EMI and conducted EMI. EDITOR’S NOTE Conducted EMI goes through conductors such as wires, while radiated EMI travels through the air and does not require a conductor. The noise that falls on the radio Hello readers!! We are back with volume 2 issue 6 edition of ECE frequency spectrum within the electromagnetic frequency spectrum is known as Hearld newsletter. Hope you will cherish our efforts. Firstly, An article Radio frequency interference (RFI) which is a subset of electromagnetic interference is drafted regarding the splendid convocation of the first batch of the (EMI) . RFI includes only electromagnetic currents with a frequency between 3kHz