Related Concept Videos
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
03:35Hybridization of Atomic Orbitals II
sp3d and sp3d 2 Hybridization
01:13¹H NMR: Complex Splitting
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
01:32UV–Vis Spectroscopy of Conjugated Systems
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is the extent of conjugation in the...
One of the factors influencing λmax is the extent of conjugation in the...
01:23IR Spectrum Peak Broadening: Hydrogen Bonding
The vibrational frequency of a bond is directly proportional to its bond strength. As a result, stronger bonds vibrate at higher frequencies, while weaker bonds vibrate at lower frequencies. The stretching vibration of the strong O–H bond in alcohols and phenols (very dilute solution or gas phase) appears as a sharp peak at 3600–3650 cm−1.
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular hydrogen bonding...
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular hydrogen bonding...
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Isomeric multi-hydrogen-bonding enables blue perovskite LEDs.
Yuanzhi Wang1, Chengxi Zhang2, Yingguo Yang3,4
1Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai, China.
Nature
|July 1, 2026
Summary
Researchers developed stable, efficient blue perovskite light-emitting diodes (PeLEDs) using isomeric molecules to form hydrogen-bonding networks. This innovation enhances perovskite stability and boosts electroluminescence performance for vibrant displays.
Area of Science:
- Materials Science
- Optoelectronics
- Chemistry
Background:
- Perovskite light-emitting diodes (PeLEDs) show great promise, but blue PeLED performance lags due to instability issues.
- Higher voltages for blue emitters exacerbate perovskite's inherent ionic instability.
Purpose of the Study:
- To enhance the efficiency and stability of blue PeLEDs.
- To overcome the limitations of current blue emitter performance in PeLEDs.
Main Methods:
- Constructing hydrogen-bonding networks within perovskite and at interfaces using isomeric molecules (OBCl and NBCl).
- Utilizing O-benzylhydroxylamine hydrochloride (OBCl) as a hydrogen-bonding donor to stabilize the perovskite structure and reduce hole energy barrier.
- Incorporating N-benzylhydroxylamine hydrochloride (NBCl) as both donor and acceptor sites for enhanced hydrogen bonding.
Main Results:
- Achieved saturated blue emissions with external quantum efficiencies of 16.8% at 463 nm and 22.0% at 468 nm.
- Demonstrated significantly improved device stability.
- Enhanced perovskite structural stability and preferential film orientation through isomeric molecular hydrogen bonding.
Conclusions:
- Isomeric molecular hydrogen bonding effectively improves blue PeLED efficiency and stability.
- The developed method represents a state-of-the-art approach for pure- and deep-blue PeLEDs.
- This advancement paves the way for widespread application of PeLED technology in full-color displays.