Doped and non-doped blue organic light-emitting diodes based on AIEgens with high exciton utilization efficiency and external quantum efficiency

Jayaraman Jayabharathi,Venugopal Thanikachalam,Sekar Sivaraj,Jagathratchagan Anudeebhana

doi:10.1039/d1ma00706h

Jayaraman Jayabharathi, Venugopal Thanikachalam + Show 2 more

Open Access

https://doi.org/10.1039/d1ma00706h

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Journal: Materials Advances	Publication Date: Jan 1, 2021
Citations: 9	License type: CC BY 3.0

Affiliation: Annamalai University

Abstract

Non-doped OLEDs with NSPI-DVP and CNSPI-DVP show high exciton utilization efficiency of 36.00 and 64.00%, power efficiency of 4.99 and 4.72 lm W−1, external quantum efficiency of 3.2 and 5.3% and current efficiency of 5.61 and 5.03 cd A−1, respectively.

Highlights

High-performance blue organic light-emitting diodes (OLEDs) have been attracting attention constantly because of their significant application potential in displays.[1,2] Blue emitters lag behind red and green emitters owing to a wide band gap, which results in inefficient carrier injection and unfavourable electrical behavior.[3]
For structure–activity analysis, frontier molecular orbital (FMO) investigations of NSPI-DVP and CNSPI-DVP were carried out using the DFT method (Fig. 1 and Table 1)
Average size of CNSPI-DVP is larger when compared to NSPIDVP, which leads to a lower photoluminescence quantum yield (PLQY) because of more contribution of molecules on the

Summary

Introduction

High-performance blue organic light-emitting diodes (OLEDs) have been attracting attention constantly because of their significant application potential in displays.[1,2] Blue emitters lag behind red and green emitters owing to a wide band gap, which results in inefficient carrier injection and unfavourable electrical behavior.[3]. 2-styryl-1H-phenanthro[9,10-d]imidazole (NSPI-DVP) and (E)-4-(5,10bis(4-(2,2-diphenylvinyl)phenyl)-2-styryl-1H-phenanthro[9,10-d] imidazol-1-yl)-1-naphthonitrile (CNSPI-DVP) consisting of AIE active triphenylethene (TPE) unit at C5 and C10 positions of phenanthrimidazole having D–A structures providing moderate conjugation when compared to C2 substitution and alleviating the ACQ effect. These luminogens having branched naphthyl moiety at azomethine nitrogen restricted the intermolecular interactions.[25] Theoretical and photophysical studies reveal that NSPI-DVP and CNSPI-DVP having HLCT behaviour with LE state (low-lying) and CT state (high-lying), enhanced the exciton utilisation efficiency (EUE). The doped OLEDs with CBP:x wt% NSPI-DVP (EQE-7.60/8.98%) and CBP:CNSPI-DVP (EQE-8.12/ 9.81%) show higher efficiencies than those of non-doped devices

Molecular design strategy

Synthesis of mechanofluorochromic materials

Thermal stability and electrochemical properties

The photophysical properties

Mechanochromism

Electroluminescent studies

Conclusion