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Abstract Solar-driven CO2 reduction to yield high-value chemicals presents an appealing avenue for combating climate change, yet achieving selective production of specific products remains a significant challenge. We showcase two osmium complexes, przpOs, and trzpOs, as CO2 reduction catalysts for selective CO2-to-methane conversion. Kinetically, the przpOs and trzpOs exhibit high CO2 reduction catalytic rate constants of 0.544 and 6.41 s−1, respectively. Under AM1.5 G irradiation, the optimal Si/TiO2/trzpOs have CH4 as the main product and >90% Faradaic efficiency, reaching −14.11 mA cm−2 photocurrent density at 0.0 VRHE. Density functional theory calculations reveal that the N atoms on the bipyrazole and triazole ligands effectively stabilize the CO2-adduct intermediates, which tend to be further hydrogenated to produce CH4, leading to their ultrahigh CO2-to-CH4 selectivity. These results are comparable to cutting-edge Si-based photocathodes for CO2 reduction, revealing a vast research potential in employing molecular catalysts for the photoelectrochemical conversion of CO2 to methane.

Abstract Deep‐blue multi‐resonance (MR) emitters with stable and narrow full‐width‐at‐half‐maximum (FWHM) are of great importance for widening the color gamut of organic light‐emitting diodes (OLEDs). However, most planar MR emitters are vulnerable to intermolecular interactions from both the host and guest, causing spectral broadening and exciton quenching in thin films. Their emission in the solid state is environmentally sensitive, and the color purity is often inferior to that in solutions. Herein, a molecular design strategy is presented that simultaneously narrows the FWHM and suppresses intermolecular interactions by combining intramolecular locking and peripheral shielding within a carbonyl/nitrogen‐based MR core. Intramolecularly locking carbonyl/nitrogen‐based bears narrower emission of 2,10‐dimethyl‐12,12‐diphenyl‐4H‐benzo[9,1]quinolizino[3,4,5,6,7‐defg]acridine‐4,8(12H)‐dione in solution and further with peripheral‐shielding groups, deep‐blue emitter (12,12‐diphenyl‐2,10‐bis(9‐phenyl‐9H‐fluoren‐9‐yl)−4H‐benzo[9,1]quinolizino[3,4,5,6,7‐defg]acridine‐4,8(12H)‐dione, DPQAO‐F) exhibits ultra‐pure emission with narrow FWHM (c.a., 24 nm) with minimal variations (∆FWHM ≤ 3 nm) from solution to thin films over a wide doping range. An OLED based on DPQAO‐F presents a maximum external quantum efficiency (EQEmax) of 19.9% and color index of (0.134, 0.118). Furthermore, the hyper‐device of DPQAO‐F exhibits a record‐high EQEmax of 32.7% in the deep‐blue region, representing the first example of carbonyl/nitrogen‐based OLED that can concurrently achieve narrow bandwidth in the deep‐blue region and a high electroluminescent efficiency surpassing 30%.

Of paramount significance in phosphorescent organic light‐emitting diodes (PHOLEDs) are the facts that Förster resonance energy transfer (FRET) must be sufficient and back energy transfer should be prohibited. Herein, the FRET efficiencies for high‐performance PHOLEDs based on a simple bipolar luminogen 1‐phenyl‐2‐(5′‐phenyl‐[1,1′:3′,1″‐terphenyl]‐4‐yl)‐1H‐phenanthro[9,10‐d]imidazole (PHT‐PPI) with high triplet energy of 2.44 eV are systematically investigated. As a result, with PO‐01 as dopant, the high‐performance orange PHOLED is achieved with maximum external quantum efficiency (EQEmax) of 26.14% and ultrahigh brightness of 152 000 cd m−2, which are the highest reported efficiencies for orange OLEDs with such high brightness. In addition, the green and red PHOLEDs are also fabricated with EQEmax of 15.38% and 16.12%, respectively. Furthermore, the nondoped device based on PHT‐PPI as a deep‐blue emitter is also obtained with an EQEmax of 5.12% and the Commission Internationale de L’Eclairage (CIE) index of (0.15, 0.08). More importantly, the blue, green, orange, and red devices exhibit low efficiency roll‐off, particularly, of which the orange PHOLED is extremely small (