TY - JOUR
T1 - Influence of host matrix on thermally-activated delayed fluorescence
T2 - Effects on emission lifetime, photoluminescence quantum yield, and device performance
AU - Méhes, Gábor
AU - Goushi, Kenichi
AU - Potscavage, William J.
AU - Adachi, Chihaya
N1 - Funding Information:
This research was funded by the Japan Society for the Promotion of Science (JSPS) through the “Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program),” initiated by the Council for Science and Technology Policy (CSTP). The authors thank Prof. K. Tokumaru, Dr. K. Shizu, Dr. Q. Zhang, Dr. T. Nakagawa, Prof. J.-L. Brédas, Mr. R. Kondo, Mr. T. Yonehara, and Dr. A. Mzhavia for their useful suggestions and discussions regarding the study presented in this paper.
PY - 2014/9
Y1 - 2014/9
N2 - The influence of the host molecules on the photoluminescent (PL) and electroluminescent (EL) properties of organic light-emitting diode (OLED) emitters showing efficient thermally-activated delayed fluorescence (TADF) has yet to be investigated in detail. Here we demonstrate that the choice of host can cause large variations in the PL quantum yield (ΦPL ∼15-70%) and delayed PL transient decay (τdel ∼2-70 ms) of a spiro-acridine-based TADF guest. We show that the effect of exciplex formation on ΦPL must be considered even at low concentrations of the TADF guest. Using the same TADF guest but changing the host layer, we are able to greatly vary the PL transient decay time from ∼4 to ∼70 ms while maintaining a high ΦPL ∼70%, which can lead to new applications. Detailed spectral characterization during PL decay reveals a gradually increasing singlet-triplet energy gap (ΔEST) as the origin of these observations. The time-varying ΔEST is explained based on dipole interactions between the host and guest molecules. Finally, PL and electrical considerations for host selection are discussed based on the performance of OLED devices.
AB - The influence of the host molecules on the photoluminescent (PL) and electroluminescent (EL) properties of organic light-emitting diode (OLED) emitters showing efficient thermally-activated delayed fluorescence (TADF) has yet to be investigated in detail. Here we demonstrate that the choice of host can cause large variations in the PL quantum yield (ΦPL ∼15-70%) and delayed PL transient decay (τdel ∼2-70 ms) of a spiro-acridine-based TADF guest. We show that the effect of exciplex formation on ΦPL must be considered even at low concentrations of the TADF guest. Using the same TADF guest but changing the host layer, we are able to greatly vary the PL transient decay time from ∼4 to ∼70 ms while maintaining a high ΦPL ∼70%, which can lead to new applications. Detailed spectral characterization during PL decay reveals a gradually increasing singlet-triplet energy gap (ΔEST) as the origin of these observations. The time-varying ΔEST is explained based on dipole interactions between the host and guest molecules. Finally, PL and electrical considerations for host selection are discussed based on the performance of OLED devices.
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U2 - 10.1016/j.orgel.2014.05.027
DO - 10.1016/j.orgel.2014.05.027
M3 - Article
AN - SCOPUS:84903309944
SN - 1566-1199
VL - 15
SP - 2027
EP - 2037
JO - Organic Electronics: physics, materials, applications
JF - Organic Electronics: physics, materials, applications
IS - 9
ER -