Exciton- and polaron-induced OLED degradation by combined ab-initio molecular dynamics and experiments (Progetti)

Type
Label
  • Exciton- and polaron-induced OLED degradation by combined ab-initio molecular dynamics and experiments (Progetti) (literal)
Anno
  • 2014-01-01T00:00:00+01:00 (literal)
Alternative label
  • D. Ceresoli F. Cargnoni A. Bossi (2014)
    Exciton- and polaron-induced OLED degradation by combined ab-initio molecular dynamics and experiments
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • D. Ceresoli F. Cargnoni A. Bossi (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • CNR-ISTM CNR-ISTM CNR-ISTM (literal)
Titolo
  • Exciton- and polaron-induced OLED degradation by combined ab-initio molecular dynamics and experiments (literal)
Descrizione sintetica
  • Samsung GRO 2014 (http://www.sait.samsung.co.kr/saithome/Page.do?method=main&pagePath=01_about/&pageName=gro_overview). Finanziato 100,000 USD. (literal)
Abstract
  • Organic light-emitting diodes (OLEDs) offer the potential of using both the singlet and triplet excitons in realizing 100% internal quantum efficiencies of electro-luminescence. However, the injected charge carriers (electrons and holes) may become trapped at morphological and chemical defects, and recombine non-radiatively. These phenomena, not only limit the quantum efficiency of the device, but are also responsible for the degradation of the device (leading to aging and failure), through the formation of highly reactive radical species. However, a complete understanding of the degradation pathways, beyond phenomenological models, based on atomistic/microscopic modeling, is still missing to date. Therefore, in this project, we aim at simulating by ab-initio molecular dynamics in the excited state, the fate of an electron, a hole and an electron-hole pair, electrically injected into the material. This computational framework has been used successfully by the PI [Ceresoli01,Ceresoli04,Ceresoli05] to simulate the trapping and recombination of excitons in pristine and chemically modified polyethylene (PE). There, the focus was on electrical damage of high-voltage sub-marine PE cables, and the work was done in collaboration with an industrial partner (Pirelli Cables and Systems). Our simulations, based on Density Functional Theory (DFT) were able to elucidate three different degradation pathways: (1) exciton trapping followed by radiative recombination, (2) exciton trapping followed by non-radiative recombination, (3) exciton trapping followed by bond-breaking and formation of dangerous radical species. Based on our finding, the industrial partner was able to design a chemical additive effective in stabilizing the PE cable. We will validate our computational framework on the real molecular systems and materials widely used as hole transporting layer (HTL) and emitting layer (EML) for blue-emitting OLEDs. These materials include TCTA, NPB, mCP and Firpic. The computational work is going to be complemented with the synthesis, preparation and experimental characterizations (FT-IR microscopy, EPR, accelerated aging, HPLC-MS device analysis) on real prototypes. OLEDs, mirroring the computed architectures will be fabricated in the SmartMatLab, recently established at CNR-ISTM, which is a unique facility for OLED and photovoltaic research in northern Italy. (literal)
Prodotto di
Autore CNR

Incoming links:


Prodotto
Autore CNR di
data.CNR.it