Jinzhong Niu

Columnar Self-Assembly of Cu2S Hexagonal Nanoplates Induced by Tin(IV)−X Complex as Inorganic Surface Ligand

We have prepared columnar self-assembled Cu(2)S hexagonal nanoplates induced by a Sn-X complex for the first time and demonstrated that the Sn-X complex can affect not only the morphology of the nanocrystals but also the self-assembly ability of the nanocrystals.

Highly Efficient Blue–Green Quantum Dot Light-Emitting Diodes Using Stable Low-Cadmium Quaternary-Alloy ZnCdSSe/ZnS Core/Shell Nanocrystals

High-quality blue-green emitting ZnxCd(1-x)S(1-y)Se(y)/ZnS core/shell quantum dots (QDs) have been synthesized by a phosphine-free method. The quantum yields of as-synthesized ZnxCd(1-x)S(1-y)Se(y)/ZnS core/shell QDs can reach 50-75% with emissions between 450 and 550 nm. The emissions of such core/shell QDs are not susceptible to ligand loss through the photostability test. Blue-green light-emitting diodes (LEDs) based on the low-cadmium ZnxCd(1-x)S(1-y)Se(y)/ZnS core/shell QDs have been successfully demonstrated. Composite films of poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB) and ZnO nanoparticle layers were chosen as the hole-transporting and the electron-transporting layers, respectively. Highly bright blue-green QD-based light-emitting devices (QD-LEDs) showing maximum luminance up to 10000 cd/m(2), in particular, the blue QD-LEDs show an unprecedentedly high brightness over 4700 cd/m(2) and peak external quantum efficiency (EQE) of 0.8%, which is the highest value ever reported. These results signify a remarkable progress in QD-LEDs and offer a practicable platform for the realization of QD-based blue-green display and lighting.

Size, Shape-Dependent Growth of Semiconductor Heterostructures Mediated by Ag2Se Nanocrystals as Seeds

Size- and shape-controllable Ag2Se-ZnS nanorods (NRs) and nanowires (NWs) have been synthesized successfully by the solution-liquid-solid (SLS) method. By using Ag2Se nanocrystals (NCs) as seeds and catalyst, colloidal Ag2Se-ZnS NRs and NWs with controllable diameters and lengths in ranges of 5-12 nm and 15-600 nm were successfully synthesized by altering the experimental variables, such as diameter of Ag2Se NCs, amount of precursor, reaction time, and reaction temperature. The Ag2Se NCs not only played a key role in the control of the shape of ZnS NCs but also influenced the crystal structure of ZnS NCs. The related surface photovoltage of heterostructured Ag2Se-ZnS NWs have also been studied and the formation of Ag2Se-ZnS heterostructure was confirmed. Moreover, this SLS method was successfully exploited to synthesize Ag2S-ZnS heterostructures.

Size- and shape-dependent growth of fluorescent ZnS nanorods and nanowires using Ag nanocrystals as seeds

High-quality, monodisperse, and size-controlled Ag-ZnS nanorods or nanowires have been synthesized successfully using Ag nanocrystals as seeds. Such one-dimensional colloidal Ag-ZnS nanorods or nanowires having a purposefully controlled diameter in the range of 5-9 nm and a length of 18-600 nm were obtained by altering the reaction conditions, such as concentration, reaction time, reaction temperature, and diameter of Ag nanocrystals. The conjunction interface of Ag-ZnS nanorods or nanowires consists of the (200) plane of Ag nanocrystal and (101) plane of ZnS rod or wire, the <101> directions of ZnS nanorods grow preferentially. Based on the photoluminescence and lifetime of Ag-ZnS nanorods, it was found that Ag nanocrystals enhanced the radiative rate eventually, the fluorescence intensity of Ag-ZnS nanorods can be tuned by changing the size of the Ag seeds. The Ag-ZnS nanorods or nanowires showed greatly improved optical properties as compared to ZnS nanocrystals, the maximum emission was around 402 nm and the photoluminescence quantum yield was up to 30% when 5 nm Ag nanocrystals were used as seeds.