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Title: Light emitting device comprising phosphorescent materials for white light generation

Abstract

The present invention relates to phosphors for energy downconversion of high energy light to generate a broadband light spectrum, which emit light of different emission wavelengths.

Inventors:
;
Publication Date:
Research Org.:
Universal Display Corporation, Ewing, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1149611
Patent Number(s):
8,786,179
Application Number:
13/621,739
Assignee:
Universal Display Corporation (Ewing, NJ) EFRC
DOE Contract Number:
SC0001013
Resource Type:
Patent
Resource Relation:
Patent File Date: 2012 Sep 17
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION

Citation Formats

Thompson, Mark E., and Dapkus, P. Daniel. Light emitting device comprising phosphorescent materials for white light generation. United States: N. p., 2014. Web.
Thompson, Mark E., & Dapkus, P. Daniel. Light emitting device comprising phosphorescent materials for white light generation. United States.
Thompson, Mark E., and Dapkus, P. Daniel. Tue . "Light emitting device comprising phosphorescent materials for white light generation". United States. doi:. https://www.osti.gov/servlets/purl/1149611.
@article{osti_1149611,
title = {Light emitting device comprising phosphorescent materials for white light generation},
author = {Thompson, Mark E. and Dapkus, P. Daniel},
abstractNote = {The present invention relates to phosphors for energy downconversion of high energy light to generate a broadband light spectrum, which emit light of different emission wavelengths.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Jul 22 00:00:00 EDT 2014},
month = {Tue Jul 22 00:00:00 EDT 2014}
}

Patent:

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  • Our project was primarily focused on the MYPP 2015 goal for white phosphorescent organic devices (PhOLEDs or phosphorescent organic light-emitting diodes) for solid-state lighting with long lifetimes and high efficiencies. Our central activity was to synthesize and evaluate a new class of host materials for blue phosphors in the PhOLEDs, known to be a weak link in the device operating lifetime. The work was a collaborative effort between three groups, one primarily responsible for chemical design and characterization (Chen), one primarily responsible for device development (Tang) and one primarily responsible for mechanistic studies and degradation analysis (Rothberg). The host materialsmore » were designed with a novel architecture that chemically links groups with good ability to move electrons with those having good ability to move “holes” (positive charges), the main premise being that we could suppress the instability associated with physical separation and crystallization of the electron conducting and hole conducting materials that might cause the devices to fail. We found that these materials do prevent crystallization and that this will increase device lifetimes but that efficiencies were reduced substantially due to interactions between the materials creating new low energy “charge transfer” states that are non-luminescent. Therefore, while our proposed strategy could in principle improve device lifetimes, we were unable to find a materials combination where the efficiency was not substantially compromised. In the course of our project, we made several important contributions that are peripherally related to the main project goal. First, we were able to prepare the proposed new family of materials and develop synthetic routes to make them efficiently. These types of materials that can transport both electrons and holes may yet have important roles to play in organic device technology. Second we developed an important new method for controlling the deposition profile of material so that arbitrary concentration gradients can be implemented in layers with mixed composition. These concentration profiles are known to increase device efficiency and longevity and we confirmed that experimentally. Third, we investigated a new method for analyzing degradation in devices using mass spectrometry to look for degradation products. We showed that these methods are not simple to interpret unambiguously and need to be used with caution.« less
  • The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters for the efficient utilization of all of the electrically generated excitons.
  • Novel combination of materials and device architectures for organic light emitting devices is provided. An organic light emitting device, is provided, having an anode, a cathode, and an emissive layer disposed between the anode and the cathode. The emissive layer includes a host and a phosphorescent emissive dopant having a peak emissive wavelength less than 500 nm, and a radiative phosphorescent lifetime less than 1 microsecond. Preferably, the phosphorescent emissive dopant includes a ligand having a carbazole group.
  • An organic light emitting device including a) an anode; b) a cathode; and c) an emissive layer disposed between the anode and the cathode, the emissive layer comprising an organic host compound and a phosphorescent compound exhibiting a Stokes Shift overlap greater than 0.3 eV. The organic light emitting device may further include a hole transport layer disposed between the emissive layer and the anode; and an electron transport layer disposed between the emissive layer and the cathode. In some embodiments, the phosphorescent compound exhibits a phosphorescent lifetime of less than 10 .mu.s. In some embodiments, the concentration of themore » phosphorescent compound ranges from 0.5 wt. % to 10 wt. %.« less
  • An organic light emitting device is provided. The device includes an anode and a cathode. A first emissive layer is disposed between the anode and the cathode. The first emissive layer includes a first non-emitting organic material, which is an organometallic material present in the first emissive layer in a concentration of at least 50 wt %. The first emissive layer also includes a first emitting organic material. A second emissive layer is disposed between the first emissive layer and the cathode, preferably, in direct contact with the first emissive layer. The second emissive material includes a second non-emitting organicmore » material and a second emitting organic material. The first and second non-emitting materials, and the first and second emitting materials, are all different materials. A first non-emissive layer is disposed between the first emissive layer and the anode, and in direct contact with the first emissive layer. The first non- emissive layer comprises the first non-emissive organic material.« less