Study Of Controllable Synthesis SnSe Nanoparticles And Property In Thin Film

SnSe is a significant Ⅳ-Ⅵ p-type semiconductor with a narrow band gap, direct and indirect band gap1.3eV and0.9eV, respectively, which offer a range of optical band gaps suitable for using as an absorber layer in photovoltaic devices.The focus of this study is to demonstrate a viable route of controlling Tin selenide’s structural and morphological properties by hot-injection methods using nontoxic inorganic compound as precursor. Size distribution narrowed, uniformed and pure SnSe nanoparticles and nanorods could be obtained using this method, respectively. The dissertation is organized in two parts, as follows:Firstly, hot-injection method was used for synthesizing a morphological and composition controllable SnSe nanoparticle. The effects of kinds of precursors, different chemical conditions on the morphology, structure and composition of obtained SnSe nanoparticles were systematically investigated. SnSe nanoparticles with the size of27.8nm were fabricated using Se powder as selenium source. SnSe nanoparticles have a direct band gap of1.46eV. When the precursor Sn:Se ratio(mol ratio)was1:2, the obtained nanoparticles presented a nanosheet liked SnSe2with a thickness of13.37nm; While using SeO2as selenium source by hot-injection method, a nanorod with the size of250(length)×14(width)nm SnSe nanorods were synthesized. UV-vis absorption spectra of the SnSe nanorods revealed a strong absorption in the visible light region with a direct band gap of1.40eV which is a litter higher than bulk SnSe’s because of quantum effect. Time-dependent results showed that SnSe nanorods with uniform shape were form initially, and SnSe grew in [010] direction, it is elucidated that SnSe nanorods grew in [010] direction using the Selenium dioxide’s chain structure as the template. Moreover, flower-liked SnSe2could be obtained when Sn:Se ratio was1:2in this condition.Secondly, spin-coating and doctor-blade methods were investigated to obtain the SnSe thin films using the SnSe nanoink in toluene solvent. A hole and crake free of SnSe thin film with a thickness of1.2μm was obtained by doctor-blade methods using a concentration of300mg/ml nanoink. The crystallinity of the thin film was improved by extending the annealed time. Mott-Schottky measurement showed that the SnSe thin films are p-type semiconductor which was optimal for using as the absorb layer in solar cell device.