Confining light-emitting molecular units inside a rigid porous crystal helped preserve its structure while reducing energy losses.
Researchers designed crystalline covalent organic frameworks with donor-acceptor units built into their backbones. The frameworks’ nanopores constrained these units in a way that supported thermally activated delayed fluorescence, while the rigid crystal structure limited energy losses from molecular vibrations.
The materials formed free-standing films with high photoluminescence quantum yields and were used in solution-processed organic light-emitting diodes. The abstract says the devices had competitive performance among crystalline porous emitters, but it does not give the underlying performance values.
How the pores affect light
The researchers embedded conformationally locked donor-acceptor pairs directly into the backbones of flexible covalent organic frameworks. The crystalline nanopores forced these pairs into arrangements that reduced the singlet-triplet energy gap to 0.014 electronvolts, a condition that supports thermally activated delayed fluorescence. At the same time, the rigid framework curtailed vibrational energy losses.
The approach produced free-standing films with high photoluminescence quantum yields and enabled solution-processed organic light-emitting diodes. According to the abstract, the materials maintained crystallinity, film integrity and processability, and the devices showed competitive performance among crystalline porous emitters.
Evidence and open questions
This is a journal article reporting the design and characterization of flexible crystalline covalent organic frameworks, including free-standing films and solution-processed organic light-emitting diodes. The abstract does not provide the photoluminescence quantum yields, device performance figures, testing duration, or comparison details, so the scale and durability of the reported advantages cannot be assessed from the supplied information.
