How Organic Diodes Make Light Using Special Molecules
Eastman Kodak's 1982 patent on creating light-emitting diodes (OLEDs) using organic materials, specifically a layer of porphyrinic compounds to help inject electrical charges.
Original patent title: “Organic electroluminescent cell”
Eastman Kodak's 1982 patent on creating light-emitting diodes (OLEDs) using organic materials, specifically a layer of porphyrinic compounds to help inject electrical charges. Granted to Eastman Kodak Co in 1982 with 6 claims and 1,031 forward citations, and it is now in the public domain.
Key facts
Coverage
What does this patent actually cover?
This patent describes how to build a light-emitting device, like a tiny light bulb, using organic materials. It details an 'electroluminescent cell' with a light-producing layer sandwiched between two electrical contacts (an anode and a cathode). The key innovation is adding a special 'hole-injecting zone' made of a porphyrinic compound, like phthalocyanine, right next to the anode. This layer helps electrical 'holes' (think of them as positive charges) move more easily into the light-emitting layer, making the device work better.
The gap
What does this patent NOT cover?
- Electroluminescent cells that do not use organic materials for the light-emitting zone.
- Devices where the hole-injecting zone is not made of a porphyrinic compound.
- Cells that lack a distinct hole-injecting zone between the luminescent zone and the anode.
- Electroluminescent cells where the binder material has a breakdown field strength below 10^5 volt/cm.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The crucial insight was realizing that a specific class of organic molecules, porphyrinic compounds, could act as an efficient 'bridge' to inject positive charge carriers (holes) into the organic light-emitting layer, significantly improving device performance and efficiency.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Modern OLED displays in smartphones
OLED televisions
Flexible OLED screens
Why it matters
The bigger picture
This patent is a foundational piece for modern organic light-emitting diode (OLED) technology. OLEDs are now ubiquitous in high-end smartphone screens, televisions, and flexible displays. The principles laid out by Ching W. Tang here enabled the development of efficient, thin, and flexible displays that revolutionized consumer electronics.
Filed
July 17, 1980
Granted
October 26, 1982
Market context
Who's building on this
Companies in this space
The foundational work in this patent has been built upon by countless companies in the display and lighting industries. Major players like Samsung Display, LG Display, and Universal Display Corporation (UDC) are heavily involved in developing and manufacturing OLED technology, leveraging advancements in organic materials and device architecture.
Market impact
This patent laid the groundwork for the entire OLED industry. It established the core architecture for efficient organic light-emitting devices, enabling the creation of vibrant, thin, and energy-efficient displays that have become a standard in premium consumer electronics, driving significant market growth and innovation in display technology.
Claim 1 — Plain English
What this patent covers
This patent describes how to build a light-emitting device, like a tiny light bulb, using organic materials. It details an 'electroluminescent cell' with a light-producing layer sandwiched between two electrical contacts (an anode and a cathode). The key innovation is adding a special 'hole-injecting zone' made of a porphyrinic compound, like phthalocyanine, right next to the anode. This layer helps electrical 'holes' (think of them as positive charges) move more easily into the light-emitting layer, making the device work better.
The clever bit
The crucial insight was realizing that a specific class of organic molecules, porphyrinic compounds, could act as an efficient 'bridge' to inject positive charge carriers (holes) into the organic light-emitting layer, significantly improving device performance and efficiency.
What it does not cover
- Electroluminescent cells that do not use organic materials for the light-emitting zone.
- Devices where the hole-injecting zone is not made of a porphyrinic compound.
- Cells that lack a distinct hole-injecting zone between the luminescent zone and the anode.
- Electroluminescent cells where the binder material has a breakdown field strength below 10^5 volt/cm.
Patent Journey
From filing to expiry
PatentBrief Score
Impact Score
Moderate
Citation count
40/40
Highly cited
Claim breadth
4/20
Moderate scope
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$63K – $202K
Midpoint $126K · expired or expiring · industry ×1.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
6 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Tang, C. W. (1982). How Organic Diodes Make Light Using Special Molecules (U.S. Patent No. 4,356,429). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/4356429/oled-organic-light-emitting-diode
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Organic Diodes Make Light Using Special Molecules cover?
Eastman Kodak's 1982 patent on creating light-emitting diodes (OLEDs) using organic materials, specifically a layer of porphyrinic compounds to help inject electrical charges.
Who owns patent US 4356429?
Eastman Kodak Co owns this patent, granted in 1982.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 4356429 cited by?
This patent has been cited by 1031 later patents that build on its ideas.
What problem does this patent solve?
This patent is a foundational piece for modern organic light-emitting diode (OLED) technology. OLEDs are now ubiquitous in high-end smartphone screens, televisions, and flexible displays. The principles laid out by Ching W. Tang here enabled the development of efficient, thin, and flexible displays that revolutionized consumer electronics.
What does this patent NOT cover?
Electroluminescent cells that do not use organic materials for the light-emitting zone.
Same assignee
More from Eastman Kodak Co
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