guojun liu

We report a rational design of a sulfur heterocyclic quinone (dibenzo[b,i]thianthrene-5,7,12,14-tetraone=DTT) used as a cathode (uptake of four lithium ions to form Li₄DTT) and a conductive polymer [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)=PEDOT:PSS) used as a binder for a high-performance rechargeable lithium-ion battery. Because of the reduced energy level of the lowest unoccupied molecular orbital (LUMO) caused by the introduced S atoms, the initial Li-ion intercalation potential of DTT is 2.89 V, which is 0.3 V higher than that of its carbon analog. Meanwhile, there is a noncovalent interaction between DTT and PEDOT:PSS, which remarkably suppressed the dissolution and enhanced the conductivity of DTT, thus leading to the great improvement of the electrochemical performance. The DTT cathode with the PEDOT:PSS binder displays a long-term cycling stability (292 mAh g⁻¹ for the first cycle, 266 mAh g⁻¹ after 200 cycles at 0.1 C) and a high rate capability (220 mAh g⁻¹ at 1 C). This design strategy based on a noncovalent interaction is very effective for the application of small organic molecules as the cathode of rechargeable lithium-ion batteries.

A noncovalent interaction: A sulfur heterocyclic quinone compound (DTT) and a multifunctional binder (PEDOT:PSS) were prepared and used together as a high-performance cathode in a rechargeable lithium-ion battery (see picture). Through a noncovalent interaction between DTT and PEDOT:PSS the dissolution of DTT into an electrolyte was reduced and the conductivity of DTT was enhanced.

Organic light-emitting diodes with external quantum efficiency of 38.8% are realized using a Pt-based thin-film emitting layer with photoluminescence quantum yield of 96% and transition dipole ratio of 93%. The emitting dipole orientation of the thin films fabricated using Pt complexes is investigated and the structural relationship between X-ray structural analysis and the structures in thin films are discussed based on quantum chemical calculations.

A new class of neutral bis-tridentate Ir(III) metal complexes that show nearly unitary red, green, and blue emissions in solution is prepared and employed for the fabrication of both monochrome and white-emitting organic light-emitting diodes, among which a green device gives external quantum efficiency exceeding 31%.