Study On The Synthesis And Properties Of Metal Sulfoselenide Semiconductor Nanomaterials

In recent years, metal sulfoselenide semiconductor nanomaterials have attactedmore and more attention and research due to their outstanding optical, electrical,thermal, magnetic properties. Design and development more simple, green, universalsynthetic technique to synthesis high-quality metal sulfoselenide semiconductornanomaterials, and realization effectively tuned in their size, morphology,composition, phase structure are very important significance for metal sulfoselenidesemiconductor nanomaterials to further develop their new properties, new materialsand practical application in all kinds of fields.1. We prepared high quality lead selenide (PbSe) nanocrystals with controllablesize and shape by designing a facile colloid chemical synthesis system. Five differentshapes including quasi-spherical, cubic, octahedral, cuboctahedral and star shapedmonodispersed PbSe nanocrystals were obtained, and the particle size can be easilytuned form~18nm to~50nm by varying the concentration of oleic acid (OA). Thegrowth orientation and shape evolution mechanism of as-synthesized nanoparticles indouble stabilizer surfactants was investigated in detail. In the synthesis process, whenthe PbSe nanocrystals dispersed in toluene containing excessive oleylamine (OAm)over time, the surface of nanoparticles appeared etching phenomenon, and a newframework composed of nanorods formed around the nanocrystals. Furthermore, weconstructed an ITO-PbSe-Al device based on a film of the as-synthesized PbSenanocrystal. The dark steadystate I-V characteristics of the films before and afterligand exchange revealed a broad prospect for the use of PbSe nanocrystals in lightdetection and infrared solar cells. 2. A facile colloid chemical synthesis route for preparation of high qualityternary AgInSe2semiconductor nanocrystals with orthorhombic crystal structure wasdeveloped by using silver nitrate, indium stearate, and oleylamine-selenium (OAm-Se)as precursors. The evolution process of the AgInSe2nanocrystals is investigated indetail and discussion the impact of different reaction conditions on the growth andmorphology of the as-synthesized nanocrystals. Next, alloyed AgIn(S1-xSex)2semiconductor nanocrystals with controlled composition across the entire range (0≤x≤1) was also successfully prepared by modulating the sulfur/selenium (S/Se) reactantmole ratio, and X-ray diffraction (XRD), energy dispersive X-ray (EDX), X-rayphotoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) wereused to confirm that the as-synthesized alloyed AgIn(S1-xSex)2nanocrystals arehomogeneous. The UV-vis-NIR absorption spectra revealed that the band gapenergies of the alloyed AgIn(S1-xSex)2nanocrystals could be continuously tuned form1.99eV to1.45eV with the increasing content of Se element in the nanoparticles,indicating their potential application in the photovoltaic field.3. We prepared novel quarternary Cu3AlSnS5(CATS) semiconductornanocrystals with metastable wurtzite structure by a similar colloid chemical synthesismethod as mentioned above for the first time, which OA and OAm used as surfactant.TEM images revealed the as-synthesized nanoparticles possessed monodisperse,high-crystallinity, uniform size and morphology. We defined the necessary conditionsfor the formation of metastable wz-CATS nanocrystals, and effectively tuned theshapes of the nanoparticles. UV-vis-NIR absorption spectra indicated the band gapenergy of as-synthesized nanoparticles is1.35eV. On the basis, we construct aMo-CATS-Au device which used CATS nanocrystals as light absorbing layer, andconductivity of the device under AM1.5illumination present an increase of threetimes relative to the dark state. This obvious photoresponsive behavior indicates thatthe as-synthesized CATS nanocrystals can become potential candidate as alight-absorbing layer material in solar energy conversion.4. We design a facile, relatively green and universal colloid chemical synthesisroute purposely prepared metal selenide with nanoscale structure by using 1.5-Bis(3-methylimidazole-2-selone)pentane (Pbis) as a novel Se precursor, polyolsas reaction solvent, and poly(vinyl pyrrolidone)(PVP) as surfactant. By this method,CdSe hollow nanospheres, Bi2Se3nanodiscs, ZnSe nanowires and PbSe star-shapednanostructures with relatively uniform size and morphology have been successfullyprepared. High water solubility and good dispersity is achieved due to the existence ofthe PVP in the reactive system. At the same time, the shape or phase structure of themetal selenide nanomaterials could be well controlled by adjusting the experimentalconditions. On the basis, the optical and thermoelectric properties of the productshave been characterized in detail and achieved satisfactory result. Applying Pbis as Seprecursor to the nano-synthesis technology will provide a new synthetic methods andnew materials to synthesize metal selenide nanomaterials, and then lay the foundationof the research for their new properties and the practical application in kinds of fields.