This document discusses organic light-emitting diodes (OLEDs). It describes the basic structure of OLEDs, which consists of an organic layer sandwiched between an anode and cathode. When voltage is applied, electrons and holes are injected from the electrodes and recombine in the organic layer, emitting light. The document outlines the different layers in OLEDs, including hole injection, hole transport, electron transport, and emissive layers. It notes advantages of OLEDs such as high brightness, contrast, and response time. OLEDs have applications in displays, lighting, and other areas.
Photochemistry
ELECTROMAGNETIC SPECTRUM
LAW GOVERNING ABSORPTION OF LIGHT
LAW OF PHOTOCHEMISTRY
Grotthurs-Drapper law.
Einstein Stark law of photochemical equivalence
ELECTRONIC TRANSITIONS
Jablonski Diagram
QUANTUM YIELD
Use Of Photochemistry
Chemistry of vision
Photosynthesis in plant
Formation of Vitamin D
Fluorescent dyes in traffic
Photodynamic therapy
431chem course Aljouf university, college of science, chemistry department.
. Fates of Excited State Molecules.
• Absorption and emission of electromagnetic radiation.
• Einstein coefficients, absorption probabilities.
• Fluorescence and phosphorescence.
• Internal conversion and intersystem crossing.
• Photodissociation and predissociation.
• Jablonski diagram.
. Lasers.
• Requirements for laser action.
• Population inversions.
• Properties of laser radiation.
• Examples of lasers.
• Applications in spectroscopy and photochemistry.
Dr Wael A. Elhelece.
Photochemistry
ELECTROMAGNETIC SPECTRUM
LAW GOVERNING ABSORPTION OF LIGHT
LAW OF PHOTOCHEMISTRY
Grotthurs-Drapper law.
Einstein Stark law of photochemical equivalence
ELECTRONIC TRANSITIONS
Jablonski Diagram
QUANTUM YIELD
Use Of Photochemistry
Chemistry of vision
Photosynthesis in plant
Formation of Vitamin D
Fluorescent dyes in traffic
Photodynamic therapy
431chem course Aljouf university, college of science, chemistry department.
. Fates of Excited State Molecules.
• Absorption and emission of electromagnetic radiation.
• Einstein coefficients, absorption probabilities.
• Fluorescence and phosphorescence.
• Internal conversion and intersystem crossing.
• Photodissociation and predissociation.
• Jablonski diagram.
. Lasers.
• Requirements for laser action.
• Population inversions.
• Properties of laser radiation.
• Examples of lasers.
• Applications in spectroscopy and photochemistry.
Dr Wael A. Elhelece.
more chemistry contents are available
1. pdf file on Termmate: https://www.termmate.com/rabia.aziz
2. YouTube: https://www.youtube.com/channel/UCKxWnNdskGHnZFS0h1QRTEA
3. Facebook: https://web.facebook.com/Chemist.Rabia.Aziz/
4. Blogger: https://chemistry-academy.blogspot.com/
photo redox reactions
Photoelectric Effect and Photochemical Reactions. Photons of Light and Chemical Reactions. photodissociation of O2. It was found that Stopping voltage is proportional to the frequency of the incident light but independent of the light intensity
I am attaching the list of departmental electives offered by the Department of Chemistry for The Autumn semester 2019 at IIT Kharagpur for two years MSc Students
more chemistry contents are available
1. pdf file on Termmate: https://www.termmate.com/rabia.aziz
2. YouTube: https://www.youtube.com/channel/UCKxWnNdskGHnZFS0h1QRTEA
3. Facebook: https://web.facebook.com/Chemist.Rabia.Aziz/
4. Blogger: https://chemistry-academy.blogspot.com/
photo redox reactions
Photoelectric Effect and Photochemical Reactions. Photons of Light and Chemical Reactions. photodissociation of O2. It was found that Stopping voltage is proportional to the frequency of the incident light but independent of the light intensity
I am attaching the list of departmental electives offered by the Department of Chemistry for The Autumn semester 2019 at IIT Kharagpur for two years MSc Students
Organic Light Emitting Diode works on the same principle as that of a Light emitting Diode which is Electroluminescence.
Which is a result of radiative recombination of Electrons and holes in any Semiconductor Material. These organic LEDs can be classified on several basis such as on the basis of matrix control, on the basis of type of materials used, on the basis of direction in which light exits the surface of OLED,And there several other type of OLEDs such as foldable OLED, Transparent OLED etc.
There are also many methods of manufacturing OLEDs most used of which are inkjet printing and vapor phase deposition etc.
Then finally comes the applications and advantages of this technique. As like LEDs, OLEDs also have a wide area of applications such as in VDUs, PDAs, handheld devices (Like mobile Phones, handheld Gaming consoles), and its future uses include wearable electronics. But as the coin have 2 faces so this technique also have some drawbacks like it is not waterproof and few more which include life time of the device and others.
organic electronics & it's application (OLEDs and it's types) difference between OLEDs, LCD and LED. How OLEDs leads the other lighting or display devices.
Transparent electronics is an emerging science and technology field concentrates on producing ‘invisible’ electronics circuit and optoelectronics devices. The application contains consumer electronics such as automobile windshield, transparent solar panel, transparent display and real time wearable display. In the conventional Si/III-V based electronics, the structure is based on semiconductor junction & transistor. However, the basic building material for transparent electronic devices which is to be transparent and in visible range is a true challenge. Therefore, to understand and implement such technology there are two scientific goals, to have a material which are optically transparent and electrically conductive and to implement an invisible circuitry. Development of such invisible transparent electronic devices needs expertise together from pure and applied science, material science, chemistry, physics &electronic science.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
1. UGC – HRDC, Academic Staff College, University of Mumbai
Kalina Campus, Mumbai.
Refresher course in Chemistry
-
‘Recent Development in Applied Chemistry’
2. Content of Presentation
Introduction.
Types of light emitting devices.
What is OLED?
Basic structure of OLEDs.
Working principle of OLEDs.
Parts of OLEDs.
Advantageous of OLEDs.
Feature prospective
3. Introduction
Source of Light: Lighting technologies are substitutes for sunlight.
Natural: Sun, stars, Bioluminescent (insects), etc.
Synthetic/Artificial: Burning of coal/ Wood/ scandal, lamps, LED, OLED, etc.
Solid state lighting - alternative lighting achieved by an eco-friendly, energy
efficient, new green technology, where illumination is obtained through
semiconductor devices like light-emitting diodes (LEDs), organic light-emitting
diodes (OLEDs) or light-emitting polymers (LEPs).
The traditional technologies developed so far include in candescence and
fluorescence. These technologies have all made significant progress over the
past 200 years, but appear to be saturating at efficiencies in the 1 – 25%
range.
Newly developed technology - solid-state lighting (SSL), has the potential to
reduce lighting energy usage by nearly one half.
4. There are many challenges for efficiently creating white light from semiconductor materials
with band-gaps that span the visible spectrum is extremely challenging.
Currently used lighting systems are briefly discussed below.
Types of light emitting devices
Incandescent lamps - tungsten filament lamps, which contain
vacuum.
Tungsten- halogen - tungsten filament just like a regular incandescent
lamp; how ever the bulb is filled with halogen gas.
Fluorescent lamps - low pressure of mercury vapor and emits a
small amount of blue/green radiation, but the majority is in the UV at
253.7 nm and 185 nm.
LED lamps emit visible light in a very narrow spectral band; generate
white light.
Technology Average Life time (h) Efficiency (lumen/W)
Incandescent lamp 750-1500 12-18
Halogen lamp 2000-4000 16-29
Linear fluorescent
lamp
20000 80-100
Compact fluorescent
lamp
6000-10000 60-70
White OLEDs 10000 64 OLED
LED
Fluorescent lamp
5. OLEDs: the future of light1
1. Chen Z-K, Nancy HSL, Wei H, Xu Y-S, Yong C. Macromolecules 2003;36:1009–20; Seung WK, Byung JJ, Taek A, Hong KS.
Macromolecules 2002;35:6217–2; Neef CJ, Ferraris JP. MEH-PPV: Macromol. 2000;33:2311–4; Ide N, Tsuji H, Ito N, Sasaki H,
Nishimori T, Kuzuoka Y, etal. Proc.SPIE 2008;7051:705119–21; Van Elsbergen V, Boerner H, Lobl H-P, Goldmann C, Grabowski SP,
Young E, et al. Proc.SPIE 2008;7051:70511A-1; Huang Q, Walzer K, Pfeiffer M, Lyssenko V, He G, Leo K. Appl.Phys.Lett.
2006;88:113515; Schwartz G, Reineke S, Rosenow TC, Walzer K, Leo K. Adv.Funct.Mater. 2009;19:1.
7. Basic structure of OLEDs
A single layer OLED consists of an organic layer sandwiched between two electrodes.
This organic layer performs three main functions: hole transport (ETL), electron
transport (HTL) and emission2.
The interface provides an efficient site for the recombination of the injected electron–
hole pair and results in electroluminescence - the emitter material is doped in one of the
two layers.
2. Kido J, Nagai K, Okamoto Y. Chem Lett 1990;13:657.
The basic OLED structure consists
mainly of
Indium tin oxide (ITO)
Hole transport layer
Electron transport layer
Emitting layer
Glass substrate
Metallic cathode
8. Working Principle of OLEDs
Organic molecules are electrically conductive - delocalization of pi-electrons/non-
bonding electrons caused by conjugation over all or part of the molecule.
At applied voltage - the anode is positive and cathode is negative.
Electron injected into the LUMO of the organic layer at the cathode and withdrawn from
the HOMO at the anode.
Intensity or brightness of the light depends on the amount of electrical current applied.
Frequency of emission - band
gap of the emission material
positive
HOMO
LUMO
10. Anode of OLEDs
Anode of an OLED must be
transparent in order to inject holes into organic layers
highly conductive in order to achieve a device with
high performance and efficiency.
Indium tinoxide (ITO) - used anode material with low
roughness and high work function (ΦW = 4.5 to 5.1 eV),
which is high enough to inject holes into the highest
occupied molecular orbital (HOMO) of the organic
materials.
Good electrical conductivity, high transparency (90%)
to visible light and excellent adhesion to the substrates.
In efficient flexible OLEDs with modified graphene
anode.
11. Hole injection layer (HIL)
The materials with high positive charge mobility, electron blocking capacity
and high glass transition temperature.
Examples: 4,4’,4’’-tris(N-3-methylphenyl-N-phenylamino) triphenylamine (m-
MTDATA) and copper phthalocyanine (CuPc) are the examples of materials used
for hole injection layer.
copper phthalocyanine 4,4’,4-tris(N-3-methylphenyl-N-phenylamino)
triphenylamine
12. Hole transport layer (HTL)
Materials having low ionization potential, low electron affinities and high hole mobility.
Function as hole transporting materials by accepting and transporting hole carriers with a
positive charge.
Examples: N,N’-diphenyl-N,N’-bis(3-methylphenyl)1,1’-biphenyl-4, 4’-diamine (TPD),
N,N’-diphenyl-N,N’-bis(1-naphthylphenyl)-1,1’-biphenyl-4,4’-diamine (NPB) and 1,10-
bis(di-4-tolylaminophenyl)cyclohexane (TAPC).
TPD NPB TAPC
13. Electron transport layer (ETL)
Materials having good electron transporting and hole blocking properties, high
electron affinities together with high ionization potential.
• electron conductive pathway for negative charge carriers to migrate from the cathode
into the emission layer. Most common ETL materials are Aluminum tris-8-
hydroxyquinoline (Alq3) and 9,10-di(2-napthyl)anthracene (ADN).
Aluminum tris-8-hydroxyquinoline 9,10-di(2-napthyl)anthracene
14. Emissive layer (EML)
A layer in between HTL and ETL - emitter of visible photons - emissive layer (EML).
Organic molecules or polymers or dendrimers with high efficiency, life time and colour
purity, a high glass-transition temperature to obtain devices with longer lifetime.
Colour required – depends on energy gap i.e., the distance between HOMO and LUMO
lies such that the energy released during recombination will be within the desired
wavelength.
Examples: 4,4,N,N’-dicarbazolebiphenyl (CBP) and 1,3-bis(9-carbozoyl)benzene (mCP)
are recently developed.
CBP
mCP
20. OLEDs: future perspectives
Cell Phone screens
Keyboards (Optimus Maximus)
Light
OLEDs: Applications
Wallpaper lighting defining
new ways to light a space
Scroll laptop
Cell phones
21. Many research groups around the world are investigating various organic LEDs:
Flexible polymer OLEDs
Devices based on dendrimers
Devices into display by easy and cheap fabrication techniques.
Introduction of graphene as the device substrate, ITO is going to be replaced
by graphene.
Currently more than 80 companies, nearly 70 universities and other non-industrial
laboratories worldwide are engaged in the field of OLEDs.
OLEDs: Current Status of Research
24. Efficiency: transportation and recombination of electrons and holes in organics
constitute a current. The internal quantum efficiency (ηint) of
an OLED is defined as the number of photons produced within the device (Nin) over
the number of electrons injected (Nelectron) per unit time.
The external quantum efficiency (EQE) is one of the most important figure of merit of
OLEDs; it is defined as the ratio of photons out coupled from the device to the electrons
generated within the device. The best OLEDs have an EQE of about 25%.
The light generation mechanism in OLEDs is due to the radiative recombination of excitons
on electrically excited organic molecules. Light is generated from thin organic emitting layer
spontaneously in all the directions and propagates via various modes, that is, external
modes (escape from the substrate surface), substrate-, and ITO/organic wave guided modes
due to total internal reflection.
Light out coupling
25. efficiency of such a device strongly depends on how good holes and
electrons can be conducted. If either electrons or holes are trapped by
defects, meaning that they cannot contribute to the current anymore,
then an excess of one type of charge exists. For example, in the case that
holes are trapped, there are more electrons than holes, meaning only a
part of the electrons can create light and the efficiency of the OLED is
reduced.
Charge transfer efficiency of HIL, HT, ET:
time of flight of OLED
Time of flight. To measure mobility you create a thick film of the organic material,
place it over the top of a transparent electrode and on the side place a collection
electrode. Then fire a laser at a wavelength that will photogenerate charge carriers.