A PCDTBT:PC₇₁BM solar cell adopted by a ternary strategy with PDTSTPD achieves an overall PCE of 20.8% under indoor illumination.

Efficient Förster energy transfer from a phosphorescent sensitizer to a thermally activated delayed fluorescent terminal emitter constitutes a potential solution for achieving superb blue emissive organic light-emitting diodes, which are urgently needed for high-performance displays. Herein, we report the design of four Ir(III) metal complexes, f-ct1a ‒ d, that exhibit efficient true-blue emissions and fast radiative decay lifetimes. More importantly, they also undergo facile isomerization in the presence of catalysts (sodium acetate andp-toluenesulfonic acid) at elevated temperature and, hence, allow for the mass production of either emitter without decomposition. In this work, the resulting hyper-OLED exhibits a true-blue color (Commission Internationale de I’Eclairage coordinate CIE_y = 0.11), a full width at half maximum of 18 nm, a maximum external quantum efficiency of 35.5% and a high external quantum efficiency 20.3% at 5000 cd m^‒2, paving the way for innovative blue OLED technology.

Herein, a series of blue‐emitting Ir(III) phosphors is reported based on the cyclometalating N‐heterocyclic carbenes (NHCs), in which the typical benzimidazolylidene entity is now replaced by a new 7,9‐dihydro‐8H‐purin‐8‐ylidene unit. The two extra‐nitrogen atoms of benzimidazolylidene entity that are successfully fined turn the emission to the true‐blue region. As the proof of concept, both experimental measurement and theoretical calculation of these emitters are conducted, revealing high photoluminescence quantum yields up to 92%, peak maximum located in the region 420–490 nm, and radiative lifetime lower than 1 μs, depending on their stereochemical configuration (i.e., meridional or facial), together with distinctive phenyl cyclometalating appendage. Their photophysical characteristics are among the best of carbene‐based Ir(III) blue phosphors. Blue phosphorescent organic light‐emitting diode (OLED) using one representative derivative m‐2tBu as sole dopant emitter achieves a high external quantum efficiency (EQE) up to 17.0%, and a small efficiency roll‐off of 16% at 1000 cd m⁻². Furthermore, a true‐blue hyperphosphorescent OLED with 25 wt% of m‐2tBu as sensitizer and 2 wt% of N⁷,N⁷,N¹³,N¹³,5,9,11,15‐octaphenyl‐5,9,11,15‐tetrahydro‐5,9,11,15‐tetraaza‐19b,20b‐diboradinaphtho[3,2,1‐de:1′,2′,3′‐jk]pentacene‐7,13‐diamine (ν‐DABNA) as emitter is also fabricated, giving excellent performance with maximum EQE up to 22.0% and Commission Internationale de l’Éclairage (CIE)_xy coordinates of (0.120, 0.155).