Efficient green-phosphorescent light-emitting diodes based on polymeric binary-host systems

Carbazole-based polymers as hosts for solution-processed organic light-emitting diodes: Simplicity, efficacy

“…Carbazole is among the most stable wide bandgap molecules that was extensively studied for the design of low molecular weight or oligomeric hosts [66], fully justifying the development of polymeric host with this molecule. As appealing features of PVK, this polymer exhibits a high glass transition temperature (200°C), a high triplet energy level (E T = 2.5 eV), a good solubility in common organic solvents and excellent film-forming properties, rendering this polymer of great interest for OLEDs [67][68][69][70]. However, PVK is characterized by a hole-dominated transportation, limiting its scope of usability [71,72].…”

Carbazole based polymers as hosts for blue iridium emitters: synthesis, photophysics and high efficiency PLEDs

“…4 A major issue for the improvement of the efficiency of blue PLEDs is nding suitable host polymers for deep blue phosphorescent dopants, as these require high triplet energy to conne triplet excitons on the phosphorescent dopant. Poly(vinylcarbazole) (PVK) has been extensively used as a hole transporting host for red or green emitting devices [5][6][7][8] reaching up to $40 cd A À1 current efficiency 9 and many people are turning to PVK as a host for blue phosphorescent dopants. [10][11][12][13][14][15] However PVK forms lower energy triplet dimers which can quench blue dopants in PLEDs.…”

Poly(2-(N-carbazolyl)ethyl acrylate) as a host for high efficiency polymer light-emitting devices

“…This non-conjugated polymer 38 proved to be an excellent candidate to host wide-bandgap phosphors. Notably, this poly- 39 mer exhibited a high thermal stability (T d = 322°C), a glass transition temperature (T g ) of 40 91°C and the disrupted p-conjugation of the polymer main chain enabled to keep the wide 41 bandgap of carbazole, making this polymeric host a suitable candidate for wide bandgap 42 triplet emitters. When tested as host for FIrpic and Ir(ppy) 3 , the resulting blue and green 43 light-emitting devices showed a maximum luminous efficiency of 18.25 and 17.74 cd/A, 44 respectively, that are comparable to that reported for other carbazole-based oxygen-rich 45 polymeric hosts.…”

“…This polymer is largely used for 84 hole transport materials because of its good solubility in 85 common organic solvents and excellent film-forming prop-86 erties [36]. Due to its high glass-transition-temperature 87 (200°C) and high triplet energy level (3.0 eV), PVK is also 88 extensively regarded as a polymeric host [37][38][39][40]. The 89 non-conjugated character of this polymer leads to a triplet 90 energy level that is nearly identical to that of a single car-91 bazole unit [41].…”