Research

PAHs

Polycyclic aromatic hydrocarbons (PAHs) have several aromatic rings. The most basic of these molecules are naphthalene and three-ring anthracene. They can be grouped into three types: Planar, Hetero, and Stereo PAHs. We study different PAHs and synthesize them as functional materials for future organic electronics.

TADF

Recently, we have been greatly interested in pure organic materials with specific molecular shapes and bipolar structures. Especially for metal-free molecules with thermally activated delayed fluorescence (TADF), they have become popular in optical materials and photoelectronics. The basic rules for TADF molecular design are introduced here. Generally, the molecule is constructed by three components: electron donor, electron acceptor, and bridge. With TADF design, the molecule contains a higher triplet energy state than a conventional organic emitter, resulting in a low ΔEST and activating reverse intersystem crossing (RISC) process to emit TADF.

Adv. Mater. 2014, 26, 7931

According to spin statistics, only 25% of singlet excitons can be utilized the limit of seized in traditional OLED; efficiency is around 5 to 7.5%. When applying TADF molecules in the OLED emitting layer, these emitters can utilize all excitons (singlet and triplet) under electrical excitation to achieve high external quantum efficiency (EQE), 20~30%. Our group has even achieved devices with an EQE exceeding 30%.

OLED

An organic light-emitting diode (OLED) is a flat light emitting technology, in which the emissive electroluminescent layer is a film of organic compound. OLED screen can be made thinner, lighter, higher-response and more flexible than the LCD display. With our well-designed molecules (exhibit highly horizontal orientation) and TADF technology, we have achieved record-high OLEDs.

Future Electronics

Electronic devices are ubiquitous in our everyday life, especially portable ones. Organic electronics have several attractive properties: lightweight, low cost (carbon-based materials), electrical conductivity (polymeric conductors), and comparatively high mechanical flexibility. One of the future electronics is the flexible display. This technology is involved in building a rollable display composed of electronic ink, OFET, OLED, and other organic electronics.

We are excited to build these future technologies with our well-designed materials.

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