TY - JOUR
T1 - Tuning Hole-Injection in Organic-Light Emitting Diodes with Self-Assembled Monolayers
AU - Gkeka, Despoina
AU - Hamilton, Iain
AU - Stavridis, Thalis
AU - Liu, Zhongzhe
AU - Faber, Hendrik
AU - Naphade, Dipti
AU - Marčinskas, Mantas
AU - Malinauskas, Tadas
AU - Harrison, George
AU - Adilbekova, Begimai
AU - Maksudov, Temur
AU - Yuan, Yue
AU - Kaltsas, Dimitrios
AU - Tsetseris, Leonidas
AU - Getautis, Vytautas
AU - Lanza, Mario
AU - Patsalas, Panos
AU - Fatayer, Shadi
AU - Anthopoulos, Thomas D.
N1 - Publisher Copyright:
© 2024 American Chemical Society.
PY - 2024/7/31
Y1 - 2024/7/31
N2 - Improving hole injection through the surface modification of indium tin oxide (ITO) with self-assembled monolayers (SAMs) is a promising method for modulating the carrier injection in organic light-emitting diodes (OLEDs). However, developing SAMs with the required characteristics remains a daunting challenge. Herein, we functionalize ITO with various phosphonic acid SAMs and evaluate the SAM-modified anodes in terms of their work function (WF), molecular distribution, coverage, and electrical conductivity. We fabricate and characterize green phosphorescent SAM-based OLEDs and compared their performance against devices based on the conventional poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) hole-injection layer. We find that the usage of [2-(3,6-diiodo-9H-carbazol-9-yl)ethyl]phosphonic acid (I-2PACz) SAM yields devices with superior performance characteristics, including a maximum luminance of ∼57,300 cd m-2 and external quantum efficiency of up to ∼17%. This improvement is attributed to synergistic factors, including the deep WF of ITO/I-2PACz (5.47 eV), the formation of larger I-2PACz molecular clusters, and the intrinsic I-2PACz dipole, that collectively enhance hole-injection.
AB - Improving hole injection through the surface modification of indium tin oxide (ITO) with self-assembled monolayers (SAMs) is a promising method for modulating the carrier injection in organic light-emitting diodes (OLEDs). However, developing SAMs with the required characteristics remains a daunting challenge. Herein, we functionalize ITO with various phosphonic acid SAMs and evaluate the SAM-modified anodes in terms of their work function (WF), molecular distribution, coverage, and electrical conductivity. We fabricate and characterize green phosphorescent SAM-based OLEDs and compared their performance against devices based on the conventional poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) hole-injection layer. We find that the usage of [2-(3,6-diiodo-9H-carbazol-9-yl)ethyl]phosphonic acid (I-2PACz) SAM yields devices with superior performance characteristics, including a maximum luminance of ∼57,300 cd m-2 and external quantum efficiency of up to ∼17%. This improvement is attributed to synergistic factors, including the deep WF of ITO/I-2PACz (5.47 eV), the formation of larger I-2PACz molecular clusters, and the intrinsic I-2PACz dipole, that collectively enhance hole-injection.
KW - hole-injection
KW - interlayers
KW - organic-light emitting diodes
KW - self-assembled monolayers
UR - http://www.scopus.com/inward/record.url?scp=85199032360&partnerID=8YFLogxK
U2 - 10.1021/acsami.4c08088
DO - 10.1021/acsami.4c08088
M3 - Article
C2 - 39024545
AN - SCOPUS:85199032360
SN - 1944-8244
VL - 16
SP - 39728
EP - 39736
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 30
ER -