The short device lifetimes of blue PhOLEDs: insights into the photostability of blue Ir(iii) complexes

Abstract

Computationally-guided blue phosphor design strategies to attain photostable complexes upon PhOLED operation.

Bis‐Tridentate Iridium(III) Phosphors with Very High Photostability and Fabrication of Blue‐Emitting OLEDs

“…These experimental results also corroborate the theoretical studies showing that 3 + 3 iridium skeleton can afford higher metal–ligand BDE than that of the 2 + 2 + 2 system 23. Moreover, the test also shows that the rate of photodegradation is also slower than that of SB and Px‐5 possessing bis ‐ tridentate ligands (cf.…”

“…However, the hot excited states generated by triplet–triplet annihilation of blue emitters possess an energy of ≈6 eV,23 meaning that these T d concepts are not suitable in estimating the material stability of blue emitters. To cope with this deficiency and provide better assessment on material stability, there are a number of literature reports on the use of either 400 nm LED24 or UV irradiation25 to test photostability of OLED emitters in solution and in a solid organic matrix.…”

Mer‐Ir(ppy)3 to Fac‐Ir(ppy)3 Photoisomerization

“…Facial/meridional stereoisomerism in trisbidentate Ir(III) complexes strongly determines their photophysical properties and thereby their efficiency and stability within a phosphorescence-based organic light-emitting diode (PhOLED) device. [9] In recent years, numerous computational [10][11][12] and experimental [13][14][15][16] efforts have been made to decipher the underlying degradation mechanisms, and still many open questions remain. These investigations highlight the protagonistic role of a non-previously described 3 MC (triplet metal-centred) state bearing one stretched trans Ir-N position.…”

“…These investigations highlight the protagonistic role of a non-previously described 3 MC (triplet metal-centred) state bearing one stretched trans Ir-N position. Evidence shows that the population of higher-lying excited states, and particularly, triplet metalcentered ( 3 MC) excited states, [10,16] strongly enhances these degradation processes. [1,2] To further improve their device operational lifetimes, and especially in the case of blue phosphors, it is crucial to acquire durable and efficient materials that do not suffer intrinsic chemical degradation upon PhOLED operation.…”

“…[1,2] To further improve their device operational lifetimes, and especially in the case of blue phosphors, it is crucial to acquire durable and efficient materials that do not suffer intrinsic chemical degradation upon PhOLED operation. [9] In recent years, numerous computational [10][11][12] and experimental [13][14][15][16] efforts have been made to decipher the underlying degradation mechanisms, and still many open questions remain. [9] In recent years, numerous computational [10][11][12] and experimental [13][14][15][16] efforts have been made to decipher the underlying degradation mechanisms, and still many open questions remain.…”