Lingqiang Meng

Novel Thermally Activated Delayed Fluorescence Materials–Thioxanthone Derivatives and Their Applications for Highly Efficient OLEDs

Thermally activated delayed fluorescence emitters with small energy gap between the triplet and singlet (ΔEST ), TXO-PhCz and TXO-TPA, have been successfully synthesized by combining a hole-transporting TPA/PhCz moiety and an electron-transporting TXO moiety. Both compounds display efficient solid-state luminescence with an efficient up-conversion of the triplet to singlet. OLEDs based on them exhibt high performance up to 21.5%, which is among the best reported for OLEDs.

High mobility emissive organic semiconductor

The integration of high charge carrier mobility and high luminescence in an organic semiconductor is challenging. However, there is need of such materials for organic light-emitting transistors and organic electrically pumped lasers. Here we show a novel organic semiconductor, 2,6-diphenylanthracene (DPA), which exhibits not only high emission with single crystal absolute florescence quantum yield of 41.2% but also high charge carrier mobility with single crystal mobility of 34 cm2 V−1 s−1. Organic light-emitting diodes (OLEDs) based on DPA give pure blue emission with brightness up to 6,627 cd m−2 and turn-on voltage of 2.8 V. 2,6-Diphenylanthracene OLED arrays are successfully driven by DPA field-effect transistor arrays, demonstrating that DPA is a high mobility emissive organic semiconductor with potential in organic optoelectronics.

Highly Efficient Orange and Red Phosphorescent Organic Light‐Emitting Diodes with Low Roll‐Off of Efficiency using a Novel Thermally Activated Delayed Fluorescence Material as Host

MTXSFCz with thermally activated delayed fluorescence is synthesized. Orange and red phosphorescent organic light-emitting diodes (PHOLEDs) with low efficiency roll-off exhibit external quantum efficiencies (EQE) up to 11.8% and 15.6%. The efficient upconversion from triplet to singlet of the host reduces the triplet density and thus affords a low efficiency roll-off of PHOLEDs.

Highly Efficient Nondoped Organic Light Emitting Diodes Based on Thermally Activated Delayed Fluorescence Emitter with Quantum-Well Structure

Highly efficiency nondoped thermally activated delayed fluorescence (TADF) organic light emitting diodes (OLEDs) with multiquantum wells structure were demonstrated. By using an emitting layer with seven quantum wells, the nondoped TADF OLEDs exhibit high efficiency with EQE of 22.6%, a current efficiency of 69 cd/A, and a power efficiency of 50 lm/W, which are higher than those of the conventional doped OLED and among the best of the TADF OLEDs. The high performance of the devices can be ascribed to effective confinement of the charges and excitons in the emission layer by the quantum well structure. The emission layer with multiquantum well structure is demonstrated to be cost effective for highly efficient nondoped TADF OLEDs and holds great potential for organic electronics.

A cross-dipole stacking molecule of an anthracene derivative: integrating optical and electrical properties

Cross-dipole stacking has been addressed as a preferred motif for solid state emission, but inefficient for charge transport. Here we synthesize a new anthracene derivative, which adopts cross-stacking in the solid state with a solid state fluorescence up to 77.3% and a hole mobility of 1.47 cm2 V−1 s−1, integrating optical and electrical properties successfully. As far as we know, it is the first report of organic field-effect transistors based on cross-dipole stacking molecules.

Naphthyl substituted anthracene combining charge transport with light emission

By simply introducing the naphthyl group into the 2-position of anthracene, we synthesized a new anthracene derivative, NaAnt, which showed good charge transporting properties up to 1.10 cm2 V−1 s−1 and a photoluminescence quantum yield (PLQY) of 40.30%. The results indicate its potential applications in multifunctional optoelectronics.

Nonvolatile memory devices based on carbon nano-dot doped poly(vinyl alcohol) composites with low operation voltage and high ON/OFF ratio

Carbon nano-dots were synthesized by a hydrothermal method and integrated into the poly(vinyl alcohol) matrix as charge carrier trapping centers for nonvolatile memory devices. The devices with the configuration of ITO/carbon nano-dots-PVA/Ag exhibited bistable electrical switching at low voltage, long retention time and excellent reading stability.

Online evaluation system for the photo-physical properties of organic photoelectric materials and device integrated with the device fabrication instrument

Organic photoelectric materials have showing a wide application prospect in the fields of energy, environment, information and biology because of their unique advantages. However, it is still not clear for us to understand some basic photo-physical processes (i.e. energy transfer, charge transfer, charge separation and recombination, etc.), which has affected the performance of materials and devices. This is very incompatible with the rapidly growing demand of the organic photoelectric materials and devices, and it has been one of the core problems that constraints the further applications of organic photoelectric materials and devices. The lack of the necessary systems and means is a major reason. Thus, it is a very necessary urgent task to develop new methods and technologies to evaluate the photo-physical properties of organic photoelectric materials and equipment systems. In this paper, an on-line research system for photo-physical properties is established to detect the intrinsic character of the organic photoelectric materials and devices, which integrates the fabrication instrument of the film materials and devices with the online measuring equipment combing with the high vacuum technology and the steady state transient spectrum measurement. A standard OLED device was fabricated and the electrluminescence spectra, current density, brightness, current efficiency and the power efficiency were got using this system avoiding the affect of the air and water. The results indict this system not only plays an important promoting role for the theoretical research of organic photoelectric materials and devices, but also helps improving the research level of organic photoelectric materials and devices. This work is expected to produce some potential innovating results with the international advanced level and make contributions to needs of national strategy.