Blue phosphorescent tetradentate pyridyl–carbolinyl Pt­(II) complexes, Pt­(ppzOclpy-Me), Pt­(ppzOclpy-iPr), and Pt­(ppzOclpy-mesi), were purposefully synthesized and investigated with their photophysical and luminescent properties. The complexes, incorporating with carbolinyl moieties, have twisted planar structure. X-ray crystallography revealed that the intraligand N···H–C hydrogen bond reversely turned the twisty pyridyl moiety back into the chelating plane. Computational analyses confirmed that the metal-to-ligand charge-transfer transition character appears in the singlet manifolds. However, the ligand-centered transitions rule in their triplet states, which accounts for the phosphorescent emission. The Pt­(II) complexes emit blue light with peak wavelengths (λmax) of 461–481 nm and moderate photoluminescent quantum yields (Φ = 34–46% in dichloromethane and Φ = 44–52% in films). The electroluminescent devices were fabricated by solution processes, giving blue emissions peaking at around 470 nm.

Described herein is a stable complex, Pt(mpzpyOczpy-mesi), embodying efficient, narrow blue emission. The highly twisted structure of the complex improves the stability and efficiency of photo-and electroluminescence by reducing the intermolecular interactions. The complex in solution shows high photoluminescence efficiency (>95%) and radiative decay rate (K r = 2.9 × 10 5 s −1 ) with a narrow emission spectrum. The bottom-emitting phosphorescent device, BE1, exhibits durable deep blue emission with CIE coordinates of (0.145, 0.166) and 5.2 h of LT 50 at an initial luminance of 685 cd/m 2 . Top-emitting devices, TE1 and TE2, achieve ultrapure blue color with CIE x,y values of (0.141, 0.068) and (0.140, 0.071), respectively. TE4 shows high brightness of 3405 cd m −2 at 50 mA m −2 , EQE of 10.2% at 1000 cd/m 2 , and almost negligible color deviation around (0.135, 0.096) at viewing angles of 0°−60°.

Organic scintillators, materials with the ability to exhibit luminescence when exposed to X-rays, have aroused increasing interest in recent years. However, the enhancement of radioluminescence and improving X-ray absorption of organic scintillators lie in the inherent dilemma, due to the waste of triplet excitons and weak X-ray absorption during scintillation. Here, we employ halogenated thermally activated delayed fluorescence materials to improve the triplet exciton utilization and X-ray absorption simultaneously, generating efficient scintillation with a low detection limit, which is one order of magnitude lower than the dosage for X-ray medical diagnostics. Through experimental study and theoretical calculation, we reveal the positive role of X-ray absorption, quantum yields of prompt fluorescence, and intersystem crossing in promoting the radioluminescence intensity. This finding offers an opportunity to design diverse types of organic scintillators and expands the applications of thermally activated delayed fluorescence.

Efficient and durable OLEDs of cyan, greenish yellow, yellow and white colors were fabricated in simple structures with Pt–Cpy bonded complexes, giving state-of-the-art tuning the color of electroluminescence.

The electron-rich nitro group, having higher sensitivity to environments, is attractive for constructing stimuli-responsive luminescent materials. However, it also causes the fluorescence quenching of luminogens, making a formidable challenge to...