| Photoelectric materials is an important building blocks for new information and next generation energy technologies, traditional binary semiconductor materials already have a comprehensive and in-depth research both in basic properities and its applications, developing new multiple materials and exploiting their application are urgent prerequisite for promoting relevant technological progress. In addition, in recent years, the rapid development of nanophotonics integrated nanotechnology and photonics, which mainly address in the fundamental principle of the interaction between light and matter on wavelength or subwavelength scale. Nanophotonics has put forward new challenges, but also create new opportunities in physics, chemistry, engineering, biology, medicine, and so on. In the past decade, nanophotonics has made rapid development as an independent branch of science, and also provide a new perspective to insight the interaction between light and matter, these perspectives also allows researchers to get more new physical properties and applications.The traditional binary compound semiconductor materials are 1) Ⅱ-VI semiconductor material. It constituted by the Ⅱ group elements Zn, Cd, Hg and Ⅵ elements O, S, Se, Te, the typical compounds are ZnS, CdTe, HgTe. 2) III-V semiconductor material, It constituted by Ⅲ elements Al, Ga, In and V elements P, As, Sb, the typical compound is GaAs. 3) IV-IV semiconductor material, the typical representatives are SiC and Ge-Si compound. These binary semiconductor materials because of their unique band structure and properties have been widely used in optoelectronic devices, microwave devices, infrared devices and ultra-high-speed microelectronic devices and circuits. Its properties and application of the semiconductor nanomaterials have been comprehensively developed in recent few decades. However, there is still a big gap between properties of binary semiconductor and new application demand, therefore the focus of research opportunities be extended to the new multiple semiconductor materials, trying to find new materials with new properties and applications in new scenario, which is research opportunities and also an urgent need. Although there are a number of new multiple compounds were prepared and researched, there is still a huge space can be expand on the depth and breadth aspects of applications.This dissertation reports the synthesis multiple chalcogenide semiconductor nanomaterials through low-cost, facial solvothermal method and its optical and electrical properties research. The morphology control also researched for the preparation of device applications. Finally, the device fabrication demonstrated the potential application in optoelectronic device. The specific studies as follows:(1) Starting from binary CuS and Bi2S3, the synthesis of ternary Cu-Bi-S nanomaterials, including Cu3Bi3S7 nanorods Cu4Bi4S9 nanowires and Cu4Bi4S9 nanoribbons was systematically studied. Characterization results show that the prepared Cu-Bi-S ternary chalcogenide nanomaterials have high quality. We found that the difference between the reaction temperature and the boiling point of the solvent plays an important role in the growth process of Cu4Bi4S9 nanoribbons. High-quality Cu4Bi4S9 nanoribbons of controllable lengths up to one centimeter were synthesized by using solvents of varied boiling points(BP) and changing reaction temperatures(RT) to control the competition of collision and growth of Cu4Bi4S9 seeds and species efficiently.(2) Optical and electrical properties of the solvothermal synthesized one-dimensional Cu-Bi-S based nanomaterials were systematically investigated. The optical bandgaps of Cu4Bi4S9 NWs(0.93 eV), determined by spectroscopic measurements, is in consistent with the electrochemical bandgaps(1.05 eV) that determined by CV method, which match well with the solar spectrum. The energy levels(-5.24 eV For VB and-4.19 eV for CB) is similar with the well-known CuInS2 nanocrystals implying that Cu4Bi4S9 can be potential candidates as photovoltaic absorbers. Single nanowire devices were fabricated and their electrical transport behavior and photoconductive properties were systematically investigated. It was observed that Cu4Bi4S9 nanowire behave as typical semiconductors in the temperature region of 10-140 K, but exhibit metal-like characteristic in the temperature region of 150-300 K. The carrier transport in Cu4Bi4S9 nanowires can be described by small polarons model in moderate temperature region and variable range hopping mechanism in the low temperature region. The single nanowire devices also exhibit good photo-response characteristic, which implies the potential to be used in photodetectors applications. We further studied the application of Cu4Bi4S9 nanowires in field-emission devices. The devices exhibit a relatively low turn on fields of 6.9 V/μm. To our best knowledge, the relatively strong IR emission in range of 1200-2200 nm from Cu4Bi4S9 nanobelts was observed first time, which imply that Cu4Bi4S9 nanobelts can be potential candidates as NIR light-emitting material. Finally, our newcomers use the one-dimensional Cu-Bi-S based nanomaterials fabricated a solar cell and the photoelectric conversion efficiency reached 6.2%.(3) Cu3SbS4 nanocrystals(CAS NCs) were synthesized via a facial solvothermal method. The optical bandgaps of CAS NCs(1.44 eV), determined by spectroscopic measurements, is in good agreement with the electrochemical bandgap(1.6 eV) that determined by CV method, which match well with the solar spectrum. These imply that CAS NCs may be the potential candidates as photovoltaic absorbers. Effects of sulfide source concentration on CAS NCs growth and composition tunability were systematically investigated. Pure and nearly monodisperse CAS NCs are obtained by adding 4.5 mmol sulfide. Non-stoichiometry of CAS NCs were achieved composition control by varying the molar ratio of CuCl and SbCl3 precursors, and the [Cu]/[Sb] molar ratio of the resulting NCs could be gradually changed from 2.6 to 3.6. To demonstrate the photovoltaic application of CAS NCs, a series of inverted hybrid photovoltaic devices were fabricated with different [Cu/Sb] molar ratios of CAS NCs. The champion cell was fabricated with [Cu]/[Sb]≈3.2 yield Voc, Jsc, FF and PCE of 0.46 V, 3.01 mA/cm2, 31% and 0.43%, respectively, under AM 1.5 G illumination. This performance is ~13 times to the value of comparative devices and is comparable to the results of previous studies of hybrid solar cells reported elsewhere.(4) Impure-free kesterite Cu2ZnSnS4 nanocrystals(CZTS NCs) have been successfully synthesized via a facile solvothermal strategy. UV-Vis-INR absorption spectra of the CZTS NCs with an average crystallite size of 9.0 nm exhibited the band gap is 1.52 eV, which is in well agreement with the electrochemical band gap(1.31eV) determined by CV method. A doping growth and formation mechanism of CZTS NCs in the solvothermal reaction was proposed. The impact of sulfur source concentration and species of Sn precursor on the growth of CZTS NCs was investigated. Finally, a solar cell was fabricated, current-density measurements shown that the PCEs of the devices using CZTS NCs as the absorber layer was 0.32%, which demonstrated its potential applications as photovoltaic absorber materials. |
PDF Full Text Request