n–Doping of a Low–Electron–Affinity Polymer Used as an Electron–Transport Layer in Organic Light–Emitting Diodes
Abstract
Abstract n‐Doping electron‐transport layers (ETLs) increases their conductivity and improves electron injection into organic light‐emitting diodes (OLEDs). Because of the low electron affinity and large bandgaps of ETLs used in green and blue OLEDs, n‐doping has been notoriously more difficult for these materials. In this work, n‐doping of the polymer poly[(9,9‐dioctylfluorene‐2,7‐diyl)‐ alt ‐(benzo[2,1,3]thiadiazol‐4,7‐diyl)] (F8BT) is demonstrated via solution processing, using the air‐stable n‐dopant (pentamethylcyclopentadienyl)(1,3,5‐trimethylbenzene)ruthenium dimer [RuCp*Mes] 2 . Undoped and doped F8BT films are characterized using ultraviolet and inverse photoelectron spectroscopy. The ionization energy and electron affinity of the undoped F8BT are found to be 5.8 and 2.8 eV, respectively. Upon doping F8BT with [RuCp*Mes] 2 , the Fermi level shifts to within 0.25 eV of the F8BT lowest unoccupied molecular orbital, which is indicative of n‐doping. Conductivity measurements reveal a four orders of magnitude increase in the conductivity upon doping and irradiation with ultraviolet light. The [RuCp*Mes] 2 ‐doped F8BT films are incorporated as an ETL into phosphorescent green OLEDs, and the luminance is improved by three orders of magnitude when compared to identical devices with an undoped F8BT ETL.
- Authors:
-
[1];
[2];
[1];
[2];
[1]
- Princeton Univ., NJ (United States)
- Georgia Inst. of Technology, Atlanta, GA (United States)
- Publication Date:
- Research Org.:
- Princeton Univ., NJ (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- OSTI Identifier:
- 1923743
- Alternate Identifier(s):
- OSTI ID: 1601907
- Grant/Contract Number:
- SC0012458
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Advanced Functional Materials
- Additional Journal Information:
- Journal Volume: 30; Journal Issue: 17; Journal ID: ISSN 1616-301X
- Publisher:
- Wiley
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 36 MATERIALS SCIENCE; organic semiconductors; n-doping; conductivity; OLEDs; electron-transport layers; low-electron-affinity polymers n-doping; organic light-emitting diodes
Citation Formats
Smith, Hannah L., Dull, Jordan T., Longhi, Elena, Barlow, Stephen, Rand, Barry P., Marder, Seth R., and Kahn, Antoine. n–Doping of a Low–Electron–Affinity Polymer Used as an Electron–Transport Layer in Organic Light–Emitting Diodes. United States: N. p., 2020.
Web. doi:10.1002/adfm.202000328.
Smith, Hannah L., Dull, Jordan T., Longhi, Elena, Barlow, Stephen, Rand, Barry P., Marder, Seth R., & Kahn, Antoine. n–Doping of a Low–Electron–Affinity Polymer Used as an Electron–Transport Layer in Organic Light–Emitting Diodes. United States. https://doi.org/10.1002/adfm.202000328
Smith, Hannah L., Dull, Jordan T., Longhi, Elena, Barlow, Stephen, Rand, Barry P., Marder, Seth R., and Kahn, Antoine. Thu .
"n–Doping of a Low–Electron–Affinity Polymer Used as an Electron–Transport Layer in Organic Light–Emitting Diodes". United States. https://doi.org/10.1002/adfm.202000328. https://www.osti.gov/servlets/purl/1923743.
@article{osti_1923743,
title = {n–Doping of a Low–Electron–Affinity Polymer Used as an Electron–Transport Layer in Organic Light–Emitting Diodes},
author = {Smith, Hannah L. and Dull, Jordan T. and Longhi, Elena and Barlow, Stephen and Rand, Barry P. and Marder, Seth R. and Kahn, Antoine},
abstractNote = {Abstract n‐Doping electron‐transport layers (ETLs) increases their conductivity and improves electron injection into organic light‐emitting diodes (OLEDs). Because of the low electron affinity and large bandgaps of ETLs used in green and blue OLEDs, n‐doping has been notoriously more difficult for these materials. In this work, n‐doping of the polymer poly[(9,9‐dioctylfluorene‐2,7‐diyl)‐ alt ‐(benzo[2,1,3]thiadiazol‐4,7‐diyl)] (F8BT) is demonstrated via solution processing, using the air‐stable n‐dopant (pentamethylcyclopentadienyl)(1,3,5‐trimethylbenzene)ruthenium dimer [RuCp*Mes] 2 . Undoped and doped F8BT films are characterized using ultraviolet and inverse photoelectron spectroscopy. The ionization energy and electron affinity of the undoped F8BT are found to be 5.8 and 2.8 eV, respectively. Upon doping F8BT with [RuCp*Mes] 2 , the Fermi level shifts to within 0.25 eV of the F8BT lowest unoccupied molecular orbital, which is indicative of n‐doping. Conductivity measurements reveal a four orders of magnitude increase in the conductivity upon doping and irradiation with ultraviolet light. The [RuCp*Mes] 2 ‐doped F8BT films are incorporated as an ETL into phosphorescent green OLEDs, and the luminance is improved by three orders of magnitude when compared to identical devices with an undoped F8BT ETL.},
doi = {10.1002/adfm.202000328},
journal = {Advanced Functional Materials},
number = 17,
volume = 30,
place = {United States},
year = {Thu Feb 27 00:00:00 EST 2020},
month = {Thu Feb 27 00:00:00 EST 2020}
}
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