Thermally
activated delayed fluorescence (TADF) molecules based
on carbene–metal–amides (CMAs) have attracted tremendous
attention, but it remains a great challenge for the rational design
of such materials due to the lack of reliable molecular construction
guidelines. In this work, we perform a computational investigation
to design CMA-based TADF materials by elucidating how the location
(α, β) and number of nitrogen atoms in carbolines affect
the TADF properties. Four promising CMA-based TADF molecules with
both small splitting energy and large fluorescence oscillator strength
were successfully designed. Moreover, it was found that β-position
with one and two N atoms are promising in achieving improved TADF
performance in light of their small geometric relaxations, low energy
barriers for electron injection, small singlet–triplet splitting
energies, facile intersystem crossing, and efficient fluorescence
radiative rates. These theoretical understandings could give an in-depth
physical insight into the structure–performance relationship
of CMA-based luminescent materials, providing important guidance for
the exploration of high-performance TADF molecules.
The improving intrinsic stability, determining the life span of devices, is a challenging task in the industrialization of inverted perovskite solar cells. The most important prerequisite for boosting intrinsic stability is high‐quality perovskite films deposition. Here, a molecule, N‐(2‐pyridyl)pivalamide (NPP) is utilized, as a multifunctional resonance bridge between poly(triarylamine) (PTAA) and perovskite film to regulate the perovskite film quality and promote hole extraction for enhancing the device intrinsic stability. The pyridine groups in NPP couple with the phenyl groups in PTAA through π−π stacking to improve hole extraction capacities and minimize interfacial charge recombination, and the resonance linkages (NCO) in NPP dynamically modulate the perovskite buried defects through strong PbO bonds based on the fast self‐adaptive tautomerization between resonance forms (NCO and N+CO−). Because of the combined effect of the reduction defect density and improved energy level in the perovskite buried interfaces as well as the optimized crystal orientation in perovskite film enabled by the NPP substrate, the devices based on NPP‐grown perovskite films show an efficiency approaching 20% with negligible hysteresis. More impressively, the unencapsulated device displays start‐of‐the‐art intrinsic photostability, operating under continuous 1‐sun illumination for 2373 h at 65 °C without loss of PCE.
Stable luminescent donor–acceptor (D–A•) radical molecules with theoretically 100% internal quantum efficiency in emission have recently attracted a lot of attention, especially in light-emitting diodes. However, radicals are intrinsically highly...
Thermally activated delayed fluorescence (TADF) polymers excelling in simple, low-cost and large-area solution process ability have attracted tremendous attention recently, but it remains a great challenge for the design of...
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