Lianming Yang

Efficient nondoped white organic light-emitting diodes based on electromers

The authors report excellent white organic light-emitting diodes (WOLEDs) made of 9,9bis[4-(di-p-tolyl)aminophenyl]-2,7-bis(diphenylamino)fluorene (TADPF) or 9,9-bis[4-(di-p-tolyl)aminophenyl]-2,7-bis(9-carbazolyl)fluorene (TAKF). The superposition of a yellow emission coming from the TADPF or TAKF electromer and a blue emission originating from bis(2-(2-hydroxyphenyl)benzothiazolate)zinc gives rise to a pure white-light emission. The multilayer device using TADPF shows a maximum luminance of 5123cd∕m2, a current efficiency of 2.8cd∕A, and Commission Internationale d’Eclairage chromaticity coordinates of (0.33, 0.33). This result is the optimal for WOLEDs based on electromers so far reported.

A non-planar organic molecule with non-volatile electrical bistability for nano-scale data storage

A new non-planar organic molecule with electron donor and acceptor capabilities was synthesized for nano-scale data storage. Macroscopic I–V characteristics of organic crystalline thin films indicate that the non-planar molecule possesses good electrical bistability. Nano-scale recording dots with an average diameter of 2.5 nm were realized by scanning tunneling microscopy.

Stable and reversible optoelectrical dual-mode data storage based on a ferrocenlylspiropyran molecule

A spiropyran molecule bonded with ferrocene (SPFc) was synthesized as data storage medium. Optical recording pattern was obtained through the reversible modulation of UV and visible light on the SPFc film, which exhibited good reversibility compared with the spiropyran without ferrocene moiety. In addition, the SPFc thin film also possessed reversible electrical switching property with high ON/OFF ratio, low threshold voltage, and long retention time. Accordingly, reliable, stable, and reversible nanoscale data storage was achieved on the SPFc thin film by scanning tunneling microscopy. The results will be significant to develop multifunctional molecule and reversible multimode data storage.

A high ON/OFF ratio organic film for photo- and electro-dual-mode recording

To improve the stability of organic multifunctional materials and enhance the ON/OFF ratio, a donor-π-acceptor molecule with the triphenylamine (TPA) unit is designed and synthesized. The TPA unit can effectively stabilize the charge transferred state, and the thin film shows excellent bistable electronic switching behavior with high ON/OFF current ratio of about 105. Meanwhile, reversible and stable nanometer-scale data storage is realized on the thin film by applying pulsed voltages, and optical information storage is achieved simultaneously by utilizing fluorescence changes under UV irradiation.