Our work reveals a high dependence on charge-transfer (CT) amounts for the optimal Hartree-Fock percentage in the exchange-correlation functional of time-dependent density functional theory (TD-DFT) and the error of a vertical transition energy calculated by a given functional. Using these relations, the zero-zero transition energies of the first singlet and first triplet excited states of various CT compounds are accurately reproduced. (3)CT and locally excited triplet ((3)LE) states are well distinguished and calculated independently.

An orange-red organic light-emitting diode containing a heptazine derivative exhibits high performance with a maximum external quantum efficiency of 17.5 ± 1.3% and a peak luminance of 17000 ± 1600 cd m⁻² without any light out-coupling enhancement. The high electroluminescence performance can be ascribed to the presence of an efficient up-conversion channel from the lowest triplet state to the lowest singlet state.

Make your OLED fluorescent: an aromatic molecule based on a spiro-acridine derivative was designed, and its photoluminescence and electroluminescence were characterized. By combining the donor and acceptor moieties a small energy gap between the lowest singlet and triplet states was achieved. This design leads to an organic light-emitting diode (OLED) that rivals phosphorescent devices regarding exciton generation efficiency.

Thermoelectrics is a challenging issue for modern and future energy conversion and recovery technology. Carbon nanotubes are promising active thermoelectic materials owing to their narrow bandgap energy and high charge carrier mobility, and they can be integrated into flexible thermoelectrics that can recover any waste heat. We here report air-stable n-type single walled carbon nanotubes with a variety of weak electron donors in the range of HOMO level between ca. −4.4 eV and ca. −5.6 eV, in which partial uphill electron injection from the dopant to the conduction band of single walled carbon nanotubes is dominant. We display flexible films of the doped single walled carbon nanotubes possessing significantly large thermoelectric effect, which is applicable to flexible ambient thermoelectric modules.

An organic light emitting diode based on thermally activated delayed fluorescence (TADF) has been produced using a spirobifluorene derivative (Spiro-CN) having the donor-acceptor moieties as an emitter.