Multifunctional assistant acceptor modulated pyrenyl phenanthrimidazole derivatives for highly efficient blue and host-sensitized OLEDs

Abstract

We have designed novel blue emitters namely, PPINCN, PPINCN-TPE and PPINCN-Cz with orthogonal D-A structure to harvest maximum exciton efficiency (EUE) through reverse intersystem crossing (RISC) with hot exciton mechanism....

A triphenylacrylonitrile phenanthroimidazole cored butterfly shaped AIE chromophore for blue and HLCT sensitized fluorescent OLEDs

“…The butterfly shaped TPATPA-PPI and TPATPA-CNPPI show solvatochromic effects (positive) with red-shifts of 54 nm (TPATPA-PPI) and 43 nm (TPATPA-CNPPI) because of higher %CT and %LE characteristics in low-polarity media. 31 The HLCT behavior of TPATPA-PPI and TPATPA-CNPPI was confirmed experimentally LippertÀmataga plot:hc The small dipole moments of 6.8 and 9.7 D can be ascribed to the LE component. Hence, the two dipole moments attributed to LE and CT components reveal non-equivalent hybridization of CT with LE states in TPATPA-PPI and quasi-equivalent hybridization in TPATPA-CNPPI (Fig.…”

“…These emitters show low quantum yields in solution (26% for TPATPA-PPI and 43% for TPATPA-PPI) and high quantum yields in film (50% for TPATPA-PPI and 61% for TPATPA-CNPPI) due to AIEE which is required for efficient OLEDs (Table 1). 31…”

“…The low dopant concentration (o1 wt%) suppressed the direct charge recombination (h + -e À ) on C545T; also, at low dopant concentrations, the intermolecular distance was larger than the dopant van der Waals radii which blocked the short- recombination and enhanced the efficiency. 31 However, the short distance between the host and guest at 3 wt% decreased the efficiencies which leads to enhanced DET process T Host ! DET T Guest .…”

A highly efficient violet-blue OLED with Rec.2020 CIEy based on an orthogonal phenanthroimidazole-substituted 1,2,4-triazole derivative

“…5), which can promote the RISC process (T 5 -S 1 ) via a hot exciton channel. 4,24,31,33 As a consequence, we conjectured that the high EUE here was attributed to the HLCT mechanism and the horizontal orientation. However, in consideration of the similar electronic configurations of T 5 and S 1 , the hRISC rate should be insufficient, making the EQEs below 7%.…”

Efficient M-shaped blue emitters having a high conjugation extent with improved roll-off efficiency

“…However, locally excited (LE) states exhibit high efficiency, leading to blue-shifted emission because of higher oscillator strength from complete overlap of holes with electrons. 7 Integration of balanced CT and LE states into D-A molecules is an efficient strategy to enhance the efficiencies of BOLEDs.…”