用于太阳电池的硫化物半导体薄膜的溶液法制备及其性能研究

发布时间：2018-01-17 19:25

本文关键词：用于太阳电池的硫化物半导体薄膜的溶液法制备及其性能研究　出处：《南京航空航天大学》2011年博士论文　论文类型：学位论文

【摘要】：能源短缺和环境污染是当前人类面对的两大问题。为维持社会和经济的发展，人类必须开发清洁的可再生能源。光伏发电是一种非常有前景的可再生能源技术，有望解决能源和环境这两大问题。但目前光伏发电的成本过高，极大地限制了其大规模应用。解决这一问题的可能途径是开发低成本的太阳电池材料及低成本的制备工艺以降低太阳电池的制造成本，从而降低光伏发电的成本。本论文使用低成本的溶液方法（连续离子层吸附沉积和化学浴沉积）制备出几种可应用于太阳电池的薄膜材料（SnS、Bi_2S_3、CdS、Cu_xS、ZnS和Cu_2ZnSnS_4），详细研究了制备工艺参数对薄膜材料结构、形貌及性能的影响并对薄膜的制备机理进行了探讨。在此基础之上制备了几种结构的异质结薄膜电池原型器件，为利用溶液方法制备低成本的太阳电池打下基础。以连续离子层吸附沉积工艺制备了新颖的闪锌矿结构SnS薄膜。发现当在阳离子前驱溶液中加入氯离子时，薄膜的生长速率提高、结晶性变好、表面形貌变粗糙。对以上结果进行了分析：认为在阳离子溶液中可能会存在金属配合离子聚合形成的多聚体，在这种多聚体中锡的配位结构与闪锌矿SnS中锡的配位结构类似。这些前驱物质吸附在衬底表面并随后与硫离子发生反应，在反应过程中锡离子的配位结构保持不变从而得到了闪锌矿结构SnS。当氯离子添加到阳离子溶液中时，氯离子促进了金属配合离子的聚合过程使得更大结构的聚合体的形成成为可能，因此加入氯离子会提高薄膜的生长速率和结晶性。使用一种新的化学浴制备体系制备了闪锌矿结构及正交结构两种结构的SnS薄膜。发现沉积温度和pH值是决定最终制备的SnS薄膜晶体结构的主要因素。对由同一制备体系可制备不同结构SnS薄膜的机理进行了探讨：认为最终得到的SnS薄膜的晶体结构由在化学浴过程中出现的中间产物中锡离子的配位结构决定，即薄膜晶体结构的不同来源于沉积过程中锡源和硫源之间不同的反应路径。所制备的闪锌矿及正交结构SnS薄膜的电阻率最低分别为3300·cm及140·cm，均低于之前文献中报道的相应结构SnS薄膜的电阻率。研究了制备参数对正交结构SnS薄膜结构、形貌、电学及光学性能的影响，根据正交结构SnS薄膜的形成机理讨论了制备参数影响薄膜结构及性能的具体途径。以正交结构SnS为吸收层，制备了FTO/SnS/Bi_2S_3/Ag、FTO/CdS/SnS/Ag两种结构的异质结电池。所制备的异质结电池有明显的二极管特性，但光电转换效率较低，，尚需进一步优化。对Bi_2S_3薄膜的化学浴制备工艺进行了系统研究，研究了制备体系、制备参数、缓冲层、添加剂等对Bi_2S_3薄膜结构、形貌、光学及电学性能的影响。发现当在衬底表面先沉积一层SnS缓冲层再用化学浴沉积Bi_2S_3薄膜时，所制备薄膜的均匀性及粘附性有明显提高。使用由Bi(NO3)3、乙二胺四乙酸（EDTA）和硫代乙酰胺（TA）组成的化学浴制备体系沉积Bi_2S_3薄膜时，可得到由纳米棒状颗粒组成的薄膜，薄膜的表面较为疏松且与衬底的粘附性不好。当在化学浴制备体系中使用Bi(NO_3)_3及Na_2S_2O_3分别作为铋源及硫源时（配位剂使用柠檬酸铵或乙二胺四乙酸），容易得到表面呈树枝状的Bi_2S_3薄膜，薄膜的表面较为疏松且与衬底粘附不好。使用由Bi(NO_3)_3、柠檬酸铵（AC）和硫代乙酰胺（TA）组成的化学浴制备体系可沉积得到结构致密的Bi_2S_3薄膜。在此体系下通过提高硫代乙酰胺浓度、降低Bi(NO_3)_3浓度及在反应溶液中添加NH_4Cl等可提高薄膜表面的平整度。通过优化制备条件最终得到了致密、平整且与衬底粘附良好的Bi_2S_3薄膜。另外使用由Bi(NO3)3、柠檬酸铵（AC）和硫代乙酰胺（TA）组成的化学浴制备体系制备得到了二维纳米片状结构的Bi_2S_3薄膜。发现pH值及沉积温度是制备二维纳米片状结构Bi_2S_3薄膜的决定因素。以化学浴制备的Bi_2S_3薄膜为吸收层制备了FTO/SnS/Bi_2S_3/Ag结构的异质结电池。使用氯化镉体系及乙酸镉体系制备了六方结构且有明显的（002）择优取向的CdS薄膜，对其形貌及性能进行了对比。发现使用乙酸镉体系制备的CdS薄膜组成颗粒较小，表面更为平滑。由乙酸镉体系制备的CdS薄膜的电阻率小于由氯化镉体系制备的CdS薄膜的电阻率。乙酸镉体系制备的CdS薄膜的光学带隙略大于氯化镉体系制备的CdS薄膜的光学带隙。以CuCl2为铜源、硫脲为硫源，三乙醇胺或柠檬酸铵为配位剂制备了Cu_xS薄膜，薄膜经200℃退火后结构均为辉铜矿结构。当使用不同配位剂（三乙醇胺及柠檬酸铵）制备Cu_xS薄膜时，所制备的Cu_xS薄膜在结构、形貌及性能上的差异较小。Cu_xS薄膜退火后电阻率约在10-3·cm数量级，薄膜可见光波段透过率约50%。由化学浴工艺制备了均匀、致密且粘附良好的ZnS薄膜。所制备的ZnS薄膜光学带隙约3.9eV，其在350-1950nm波段的平均透过率约为85.6%。化学浴制备的ZnS薄膜可作为一种价格低廉的减反射膜，将ZnS薄膜沉积在制绒的硅片表面可使硅片表面反射率从14%降至7%。由溶液法制备硫化物前驱薄膜后退火的方法制备了Cu_2ZnSnS_4(CZTS)薄膜，研究了前驱薄膜结构对CZTS薄膜制备的影响。发现先使用连续离子层吸附沉积制备Cu_xS与SnS的混合层后化学浴沉积ZnS层制备前驱薄膜的工艺较有利于CZTS的形成。利用该工艺制备了均匀致密的CZTS薄膜，薄膜光学带隙为1.53eV。
[Abstract]:Energy shortage and environmental pollution are two major problems in the current human face. In order to maintain the development of society and economy, human beings must develop clean and renewable energy. Photovoltaic power generation is one of the most promising renewable energy technologies, is expected to solve the two major problems of energy and environment. But the high cost of photovoltaic power generation, greatly may limit its large-scale application. The solution to this problem is the cost of manufacturing process for preparation of solar cell materials the development of low cost and low to reduce the cost of solar cells, thereby reducing the cost of photovoltaic power generation. This paper makes the solution with low cost method (successive ionic layer adsorption and deposition and chemical bath deposition) system prepared several can be applied to
Thin film solar cells (SnS, Bi_2S_3, CdS, Cu_xS, ZnS and Cu_2ZnSnS_4), a detailed study of the process parameters of the preparation of thin film structure, influence the morphology and properties of thin film preparation mechanism was discussed. On the basis of preparation of the heterogeneous structure of several node prototype device for thin film solar cells. The solution method for preparing solar cells with low cost. In order to lay the foundation for the successive ionic layer adsorption and deposition process of zinc blende SnS thin film was prepared. When the novel found in cationic precursor solution
Chlorine ion, the growth rate of the film increased, better crystallinity, surface morphology becomes rough. The above results were analyzed: in cation solutions may exist in metal coordination polymer ionic polymerization to form, similar in this multimeric tin coordination structure and tin in zinc blende SnS the coordination structure. These precursor substances adsorbed on the substrate surface and then reacts with sulfur ions, maintaining tin ion coordination structure during the reaction constant to obtain zinc blende SnS. when chloride ions added to the cationic solution, chloride ion promoted metal ion polymerization process so as to form a larger structure the polymer becomes possible, so the chlorine ion will increase the growth rate and crystallinity of the films. The use of a new chemical bath preparation system was prepared with zinc blende structure and orthogonal structure of two kinds of structure SnS thin film deposition temperature and pH value. That is the main factor to determine the crystal structure of SnS films. The final prepared by the same preparation system of the preparation mechanism of SnS thin films with different structure are discussed that the SnS film of the final crystal structure determined by the tin ion intermediate is in coordination a structure in the chemical bath process, which is different from the crystal structure of film deposition process of tin and sulfur sources
Between the different reaction paths. The sphalerite and orthogonal structure of SnS thin films prepared by the lowest resistivity were 3300 cm and 140 cm, the resistivity was lower than the corresponding structure of SnS films previously reported in the literature. The effects of preparation parameters on the morphology structure of SnS thin films, orthogonal structure, electrical and optical properties of the influence according to the formation mechanism, discussed the preparation ways of the structure and properties of thin film parameters affect the orthogonal structure of SnS thin films. The absorption layer with orthogonal structure SnS, FTO/SnS/Bi_2S_3/Ag prepared FTO/CdS/SnS/Ag two structure heterojunction battery. The heterojunction solar cells prepared with diode characteristics obviously, but the photoelectric conversion efficiency is low that needs to be further improved.
Process of chemical bath deposition of Bi_2S_3 thin films were studied. The research of the preparation system and preparation parameters, buffer layer, morphology of additive on the structure of Bi_2S_3 thin films, and influence the electrical and optical properties. When the surface of the substrate to deposit a layer of SnS buffer layer by chemical bath deposition of Bi_2S_3 thin film, uniform and the adhesion of the films is obviously improved. By the use of Bi (NO3) 3, EDTA (EDTA) and thioacetamide (TA) composed of chemical bath deposition of Bi_2S_3 thin film preparation system, obtained films composed of nanorods, adhesion of the film and the substrate surface is loose and not good. When in the chemical bath preparation using Bi system (NO_3) _3 and Na_2S_2O_3 respectively as bismuth source and sulfur source (complexing agent using ammonium citrate or EDTA), easy to get the Bi_2S_3 film surface was dendritic, film surface Loose and substrate adhesion is not good. By the use of Bi _3 (NO_3), ammonium citrate (AC) and thioacetamide (TA) chemical bath preparation system composed of Bi_2S_3 thin films can be deposited dense structure. Under this system by increasing the concentration of thioacetamide, reducing Bi (NO_3) concentration and _3 in the reaction solution adding NH_4Cl can improve the flatness of the film surface. By optimizing the preparation conditions finally got a dense, smooth and good adhesion with substrate Bi_2S_3 film. Also used by the Bi (NO3) 3, ammonium citrate (AC) and thioacetamide (TA) composed of chemical bath preparation system Bi_2S_3 thin films were prepared two-dimensional nano lamellar structure. It was found that pH value and deposition temperature is the decisive factor of the two-dimensional Bi_2S_3 nanosheet structure. Bi_2S_3 thin films were prepared by chemical bath preparation for absorption layer prepared heterojunction FTO/SnS/Bi_2S_3/Ag cell structure.
The use of cadmium chloride and cadmium acetate system was prepared by the six party system structure and has obvious (002) preferred orientation of CdS films, the morphology and properties were compared. Found that the use of CdS thin films prepared by cadmium acetate system composed of smaller particles, the surface is smoother. The resistivity of CdS thin films by cadmium acetate system the preparation of less than CdS thin films prepared by cadmium chloride system. The optical system of CdS thin film cadmium acetate prepared the optical band gap is slightly larger than the CdS thin film cadmium chloride system for preparation of the bandgap. Using CuCl2 as the copper source, thiourea as sulfur source, triethanolamine or ammonium citrate as complexing agent preparation Cu_xS thin film was annealed at 200 C after structure are chalcocite structure. When using different complexing agent (triethanolamine and ammonium citrate) for the preparation of Cu_xS films, Cu_xS films prepared in structure, small differences in morphology and properties of.Cu_xS films on the resistance The rate of about 10-3, the level of CM, visible light transmittance of thin films is about 50%. by chemical bath process to prepare the uniform, dense ZnS films and good adhesion. ZnS films have been prepared by optical band gap of about 3.9eV, the average 350-1950nm transmittance is about ZnS 85.6%. thin films prepared by chemical bath can anti reflection film as a low price, the ZnS thin films deposited on silicon wafer surface texturing of the surface reflectance from 14% to 7%. by sulfide films by annealing precursor solution method of the preparation method of Cu_2ZnSnS_4 (CZTS) thin film, thin film of precursor structure effect on the preparation of CZTS thin films. That first using successive ionic layer adsorption and deposition of Cu_xS and SnS mixed layer after chemical bath deposition of ZnS thin film precursor process system is conducive to the formation of CZTS. CZTS films are uniform and dense in the preparation process, the optical band gap is 1.53 EV.

【学位授予单位】：南京航空航天大学
【学位级别】：博士
【学位授予年份】：2011
【分类号】：O484.4;TM914.4

【参考文献】