毕业论文-硅太阳电池工艺研究.doc

课程设计论文（设计）硅太阳电池工艺研究题 目: 硅太阳电池工艺研究 姓 名: 学 院: 光伏工程学院 专 业: 光伏材料加工与应用技术 班 级: 08级光伏（2）班 学 号: 指导教师: 目 录摘 要11. 前言22. 传统DSSC对光的利用22.1导电玻璃对光的利用22.2染料敏化剂对光的利用32.3多孔薄膜对光的利用52.3.1纳米晶TiO2颗粒尺寸对光利用研究62.3.2纳米晶TiO2薄膜厚度对光利用的影响72.4其它组成对光的利用72.4.1电解液72.4.2铂镜73.其它新型结构DSSC光利用的研究73.1二次利用光的DSSC73.2立体吸光结构的DSSC104.结论115 致谢126参考文献13硅太阳电池工艺研究摘 要：本文对传统三明治结构染料敏化太阳电池在光利用方面作了简要的论述，重点探讨了作为染料敏化太阳电池光阳极材料的TiO2薄膜和染料分子在光利用方面的特点。此外，对一些新型结构的染料敏化太阳电池在光利用方面的特点也作了简要描述。关键词：工艺研究，太阳电池，光利用，1. 前言染料敏化太阳电池（DSSC）是最近20年来，基于纳米技术发展起来的一种新型太阳电池，与传统硅电池相比，因其成本低，效率高而逐渐受到许多研究者的青睐（图1是该电池的结构示意图）。传统DSSC主要由透明导电玻璃、多孔二氧化钛薄膜、染料敏化剂、电解质溶液（或固态电解质）、对电极等组成。目前对染料敏化太阳电池的研究主要集中在TiO2薄膜材料，电解液的开发，染料分子的设计。如何提高光的利用率，从而提高DSSC的光电转换效率一直是这一领域的研究热点。图1 染料敏化太阳电池结构示意图Fig.1 Structure of dye-sensitized solar cell2. 传统DSSC对光的利用2.1导电玻璃对光的利用由于传统DSSC采用的三明治结构要求光阳极衬底必须具有透光性，因此透明导电玻璃（transparent conductive oxide，简称TCO）成为传统DSSC衬底的最佳选择，这也是目前研究者所普遍采用的。它是在玻璃表面附着一层包括In、Sb、Zn和Cd的氧化物及其多元复合氧化物薄膜材料而构成的。透明导电薄膜以掺锡氧化铟（In2O3:Sn，简称ITO）和掺氟的氧化锡（SnO2:F，简称FTO）为代表。导电膜的研究与应用较为广泛、成熟，在美、日等国已实现产业化生产。ITO经高温热处理后，面阻会呈数量级增大，而FTO在此温度热处理后性质仍然稳定，因此FTO常作为传统DSSC中TiO2薄膜的基体材料。图2所示为SOLARONIX公司三种不同FTO的紫外-可见光透过率曲线，从图中可以看出，导电玻璃在可见光范围内的最高透过率为90%左右，有一部分太阳光没有被利用，在远红外波段FTO的透过率在80%以下。选取TCO导电玻璃时，需将电阻与透过率综合考虑，一般导电率越大，透过率越小，反之亦然。追求低电阻和高的光透过率是今后TCO研究中的一个重要方向1。图2 不同玻璃基体材料的FTO紫外-可见光透过率2Fig. 2 UV-VIS transmission spectra FTO coatings on various glasses substrates2.2染料敏化剂对光的利用由导电玻璃透过的太阳光将被染料吸收，目前公认的较好的光敏染料为钌的联吡啶络合物，其基本化学式为ML2(X)2，其中M代表钌，L代表4,4-二羧基-2,2-联吡啶，X代表卤素、氰基、硫氰酸根、乙酰丙酮、硫代氨基甲酸、水等。在这一系列染料中，以N3（红染料）和N719性能最优，应用最广。N3的最大吸收峰在518nm和380nm，对应摩尔消光系数分别为1.3104 Lmol-1cm-1和1.33104 Lmol-1cm-1。但N3和N719对600nm以上的光谱响应较差，吸收光谱范围与太阳光谱不能很好匹配，因此不能有效利用这部分太阳光。2001年Grtzel等3合成了被称为“黑染料”的光敏剂，其结构式为RuL3(SCN)3 (L=三联吡啶三羧酸盐)。图3列出了N3和黑染料的分子结构图。图3 N3和黑染料分子结构图Fig.3 Molecular structures of N3 and black dye图4分别给出了N3和黑染料的吸收光谱及光吸收效率，两种光敏染料在可见光波段都具有较高的光吸收，N3的长波吸收能力较差，而在920nm处黑染料仍具有光谱响应，其吸收光谱相对N3红移了大约100nm。据报道用它作为敏化剂的电池在AM1.5太阳光照射下总的光电转换效率达到10.4%。设计合成性能更加优良的光敏染料体系，进一步提高长波范围的光吸收仍是人们的主要研究方向之一。Kubo等用N719和黑染料制备了叠层结构的染料敏化太阳电池，由于黑染料在近红外具有很好的光吸收性能，可以吸收阈值达1000 nm以内的太阳光，弥补了N719染料在长波范围吸光能力差的缺点，可以提高了电池的光谱响应范围和光电转换效率，结果表明叠层结构的电池比单独用N719或黑染料的电池的光电流提高了20%。图4 N3和黑染料的吸收光谱及光吸收效率Fig.4 Absorption spectra of N3 dye and black dye represented by absorbance and light-harvesting efficiency图5新的光敏化剂Ru(dcphen)2(NCS)2和Ru(dcbiq)2(NCS)2的分子结构式及其无水乙醇溶液中的吸收性能Fig.5 Molecular structure of new netal complex photosensitizes, Ru(dcphen)2(NCS)2 and Ru(dcbiq)2(NCS)2, and their absorption properties in ethanolic solution开发对近红外，红外波段吸收的染料，也是染料研究的一个重点。图5列出了两种新的光敏化剂Ru(dcphen)2(NCS)2和Ru(dcbiq)2(NCS)2的分子结构式及其与N3的吸收性能比较。Ru(dcphen)2(NCS)2的最大吸收峰在520nm，与N3相近，据报道利用这种染料敏化的DSSC效率达6.1%6.6%。Ru(dcbiq)2(NCS)2对大于600nm波长范围的吸收更具优势。N3染料的主要缺陷在于长波长无吸收。增大染料在近红外的吸收，同时保持短波长的光电转换效率不变，有利于提高整个太阳能电池的总效率。近年来，以Z907为代表的两亲型染料和以K19为代表的具有高吸光系数的染料敏化剂是当前多吡啶钌类染料研究的热点。2.3多孔薄膜对光的利用2.3.1纳米晶TiO2颗粒尺寸对光利用研究氧化物半导体的光化学稳定性好，是用于DSSC光阳极的宽带隙半导体材料。自Grtzel成功将纳米晶多孔薄膜引入到DSSC中，电池性能得以大幅度提高。构成TiO2薄膜的颗粒大小在10-30nm之间，颗粒间的多孔结构极大地增加了薄膜的比表面积。TiO2薄膜的粗糙因子（roughness factor）大于1000，相当于面积为1 cm2的薄膜（以厚度为10m为例），它实际的表面积达到1000cm2。考虑到纳米多孔TiO2具有高的粗糙因子，而且染料以单层吸附到TiO2颗粒的表面，所以，被吸附的染料数量大量增加（10-7molcm-2），从而导致染料在吸收峰的波长接近100 %的吸收光，增加了光的利用效率。一般说来TiO2薄膜中含有TiO2大颗粒（250-300nm），它们能有效散射入射光子，太阳光在粗糙表面内多次反射，进一步提高光吸收效率。孔隙率的多少直接影响了薄膜的性能，一般来说，孔隙率控制在60-70%间是比较合适的。图6是典型的TiO2薄膜的扫描电镜图片，其中包含了大小不等的颗粒，薄膜形成了多孔结构。图6 典型的TiO2薄膜的扫描电镜图片Fig.6 Scanning electron microscope photograph of a typical nanocrystalline TiO2 film利用散射光对提高光的收集效率，对于进一步提高染料敏化电池的光电转换效率具有积极的作用。关于这方面的研究已经有人做了详细的讨论。光在TiO2薄膜内的散射作用，可以增加入射光的入射长度，提高染料对光的吸收。通常，在制备TiO2浆料过程中，添加大颗粒的TiO2可以达到此效果。模拟计算表明，一般20nm的TiO2颗粒和作为散射中心的250-300nm大颗粒混合，可以起到增加太阳光的吸收的作用。实际上，与TiO2透明薄膜相比，大小颗粒的搭配可以提高光电流。这种工艺可以使得TiO2薄膜在低能区（如650-900nm）光谱相应提高明显。2.3.2纳米晶TiO2薄膜厚度对光利用的影响提高膜厚可以增加对光的吸收，但研究表明，薄膜厚度太大会影响电解液中的离子在薄膜中传输。为解决这一问题7，可以通过在光阳极上增加一层约几百纳米的大颗粒氧化物薄膜作为光散射结构或在薄膜中掺入少量的大颗粒TiO2来增加光的传播路径，增加电池在长波范围（600-800nm之间）的光吸收。但背反射层厚度过大会阻碍电解液在纳米多孔薄膜中的转输, 光电转换效率会降低。Nazeeruddin等8证实可以通过在以锐态矿为主的光阳极上用ZrO2充当粘接剂，粘接一层多孔绝缘的金红石型的TiO2。因为金红石晶型的TiO2在所有的白颜料中具有最高的折射率和反射率，可以将透过光阳极的光漫反射回光阳极，显著提高光的吸收，研究表明入射单色光在700 nm处光电转换效率提高了2倍。Ferber等9研究了在多孔膜中掺入少量的大颗粒TiO2，从而增加可见光在薄膜内的反射次数, 减少可见光被反射或透过薄膜，结果表明，一定量的掺杂会提高电池的光电转换效率，但大颗粒过量将影响染料的吸附量和薄膜的特性，电池效率会降低。2.4其它组成对光的利用2.4.1电解液有日本学者通过改变电解液的浓度来增加光的透过率，但是具有一定浓度的电解液虽然可以提高光的透过率，但是对光电流的研究却没有给出结果。2.4.2铂镜Nazeeruddin等10研究表明在导电玻璃上溅射一层2m厚的铂膜，则对电极具有一定的光反射作用。但Hauch等11研究认为铂是贵金属，要在满足催化条件下尽可能地少用（用量小于0.1g/m2，相当于5nm厚的额度）。Fang等12研究了10 nm至415 nm范围内的铂膜对电池效率的影响，结果表明10 nm厚的铂膜就可以获得高的光电转换效率，继续增加铂膜的厚度对电池的效率并没有明显的影响。3.其它新型结构DSSC光利用的研究3.1二次利用光的DSSC在对新结构的DSSC的光利用方面，特别是光利用对DSSC效率方面的研究还从未见有文献报道，中山大学太阳能系统研究所刘勇等设计了一种提高染料敏化太阳电池光吸收的背反射结构13，通过增加一层反光膜以达到二次利用光的目的。常用的金属反光膜有铝膜、银膜、金膜、铜膜、铑膜和铬膜等，在可见光范围，银膜具有最好的反射特性。图7 二次利用光的染料敏化太阳电池的改进结构Fig.7 The improved structure of dye-sensitized solar cells for enhancing light absorption新的可二次利用光的DSSC的结构示意图如图7所示，即在传统三明治式DSSC电池结构基础上，在镀铂的透明导电玻璃的背面附上一层银反光膜，作为背反射结构。通过银反光膜把从光阳极透过的没有被充分利用的光再次反射回光阳极，已达到二次利用光的目的。对光的反射进一步增加了光在电池光阳极中的传播路径，增加其对光的吸收，从而提高太阳电池的光电转换效率。图8 银反光膜的反射光谱Fig.8 Reflectance spectra of the silver reflection film图8是加在DSSC电池对电极背面的美国3M公司生产的银反光膜的反射光谱, 其在400-800nm之间的平均镜反射率是83.6%, 而包括漫反射的全反射率平均是94.6%, 具有较好的反光特性。图9 DSSC电池与提高光吸收结构效率对比图Fig.9 Comparison of photoelectric conversion efficiency of DSSC and that for enhancing light absorption图9是P25粉制备的DSSC电池与加反光膜提高光吸收后的光电转换效率对比图。可以看出，加反光膜后短路电流明显提高，开路电压略有增加，填充因子基本没有改变，加反光膜后电池的效率相对于传统结构电池的提高了11.4%。这种改进结构没有将背反射结构加在染料敏化太阳电池的内部。因为在电池内部光阳极的背面加背反射结构会阻碍电解液的传输。而在对电极用金属薄膜作背反射结构，由于电解液对一般金属都具有强烈的腐蚀作用，在电池的长期运行中，金属薄膜会被腐蚀掉而失去背反射的作用。同时，金属与电解液反应的杂质也可能影响电池的性能。由于对电极是镀铂的透明导电玻璃，纳米级铂膜对透明导电玻璃的透过率影响很小，因此将具有很好的反射率的银反光膜加在电池的背面是一种理想的结构。染料敏化太阳电池由于弱光性能好，与非晶硅太阳电池一样是室内的主要应用产品，不只是应用在窗户上（需要一定的光透过率），还可以应用在太阳能钟表、超市架上的显示标签和计算器上等，而这些应用对象并不需要电池透明，所以这种新的改进结构，在提高电池效率的同时，仍有较多的应用场合。3.2立体吸光结构的DSSC图10 立体吸光太阳电池结构示意图Fig.10 Schematic of a solar cell for capturing sunlight from 3-dimensional space图10是立体吸光电池结构和原理示意图，在螺旋状的钛金属丝的表面镀一层纳米晶TiO2 薄膜并吸附染料作为光阳极，镀铂的钛金属直丝作为对电极放在螺旋状光阳极的内孔中心，装在透明玻璃管内并充入电解液封装成电池。这种结构的特点是：螺旋丝状光阳极使其可以从各个角度吸收阳光，对太阳方位角和光阴影不敏感，具有被动式跟踪阳光的优点，并增大了吸收散射光的面积，通过螺旋状光阳极伸向空间增加对空间的有效吸光面积，而实际安装时只占用圆柱体电池的底面积，从而提高单位底面积上太阳电池的输出功率，节省太阳电池的占地面积。图11 入射角度对短路电流的影响（测试时间：2005年9月23日正午）Fig.11 Effects of incident angle on the short-circuit current将立体太阳电池朝南与水平面呈不同角度摆放检测到的短路电流如图11所示。 由图中可以看出电池短路电流对不同角度的摆放不敏感，但在120和300角时短路电流值最低，这主要与螺旋状光阳极的结构有关。广州9月23日正午时太阳的高度角为66.73，立体吸光电池光阳极的圆柱面在120和300角时与太阳的直接辐射光接近平行，此时对于直射来的太阳光利用较少。立体吸光电池与平面结构的明显区别是其在180角以后仍然可以工作，而平面电池由于单面吸光在这个角度范围内无法利用阳光工作。4.结论新型结构染料敏化太阳电池在光的利用方面相比传统三明治结构染料敏化太阳电池具有独特的优势。通过设计一些新型的染料敏化太阳电池，可以为今后染料敏化太阳电池提高效率提供一些新的思路。5 致谢论文的完稿意味着我毕生难忘的大学生活即将结束，我将离开我可爱的母校，尊敬的老师和亲爱的同学。面对今天已经成稿的毕业论文，我要感谢我的论文指导老师曹老师，是我的指导老师用谦虚严谨的治学态度和诲人不倦的传道、授业、解惑精神，帮助我克服种种困难，完成论文的写作。我还要感谢我的父母、同学和所有帮助过我以及给我精神动力的人。感激之情无以言表，只能千言万语汇成一句话：衷心的感谢所有我应该感谢的人，谢谢。6参考文献：1US Patent 5923457 - Electro-optic device including a low sheet resistance, high transmission transparent electrode April 2008 Vol. 24, No. 04 Display Week Preview / Honors and Awards Issue2Molecular and electronic structures of black dye; an efficient sensitizing dye for nanocrystalline TiO2 solar cells, Journal of Molecular Structure,2003,658:25-32.3Engineering of efficient panchromatic sensitisers for nanocrystalline TiO2 based solar cells. 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J Am Chem Soc,1993,115(14):6382-6390.10一种提高染料敏化太阳电池光吸收的结构的初步研究,功能材料2006,37(10):1584-158611用背反射提高染料敏化太阳电池光吸收的研究,中山大学学报, 2006,45(2),25-2812一种新的二次利用光的染料敏化太阳电池改进结构,科学通报,2006, 51(2), 230-234 13A new improved structure of dye-sensitized solar cells with reflection film, Chinese Science Bulletin,2006, 51(3), 369-37314一种螺旋丝状集成的立体吸光太阳电池,中国科学E辑, 2007,37(3)：1-10 为你提供优秀的毕业论文参考资料，请您删除以下内容，O(_)O谢谢！A large group of tea merchants on camels and horses from Northwest Chinas Shaanxi province pass through a stop on the ancient Silk Road, Gansus Zhangye city during their journey to Kazakhstan, May 5, 2015. The caravan, consisting of more than 100 camels, three horse-drawn carriages and four support vehicles, started the trip from Jingyang county in Shaanxi on Sept 19, 2014. It will pass through Gansu province and Xinjiang Uygur autonomous region, and finally arrive in Almaty, formerly known as Alma-Ata, the largest city in Kazakhstan, and Dungan in Zhambyl province. The trip will cover about 15,000 kilometers and take the caravan more than one year to complete. The caravan is expected to return to Jingyang in March 2016. Then they will come back, carrying specialty products from Kazakhstan A small art troupe founded six decades ago has grown into a household name in the Inner Mongolia autonomous region. In the 1950s, Ulan Muqir Art Troupe was created by nine young musicians, who toured remote villages on horses and performed traditional Mongolian music and dances for nomadic families. The 54-year-old was born in Tongliao, in eastern Inner Mongolia and joined the troupe in 1975.He says there are 74 branch troupes across Inner Mongolia and actors give around 100 shows every year to local nomadic people. I can still recall the days when I toured with the troupe in the early 80s. We sat on the back of pickup trucks for hours. The sky was blue, and we couldnt help but sing the folk songs, Nasun says. The vastness of Inner Mongolia and the lack of entertainment options for people living there, made their lives lonely. The nomadic people were very excited about our visits, Nasun recalls. We didnt have a formal stage. The audience just sat on the grass. Usually, the performances became a big party with local people joining in. For him, the rewarding part about touring isnt just about sharing art with nomadic families but also about gaining inspiration for the music and dance. Ulan Muqir literally translates as red burgeon, and todays performers of the troupe still tour the regions villages and entertain nomadic families, but their fame has spread around the world. On May 16 and 17, nearly 100 singers and dancers from the troupe performed at Beijings Poly Theater. Their show, titled Ulan Muqir on the Grassland, depicted the history and development of the art troupe. Being from the region allowed me to embrace the culture of Inner Mongolia and being a member of the troupe showed me where I belonged, Nasun, the art troupes president, who is also a renowned tenor, tells China Daily. During a tour in 1985, he went to a village and met an elderly local man, who told him a story about his friendship with a solider from Shenyang, capital of Northeast Chinas Liaoning province, decades ago. The solider gave the old man a handmade saddle when they bid farewell. The story inspired Nasun to write Carved Saddle, a song that later became one of his most popular numbers. Now, every year, Nasun recruits young singers and dancers for the troupe. The troupe has also designed a new repertoire, which is mostly based on the daily lives of Mongolian people, especially the lives of nomadic families, and has combined contemporary musical elements with folk songs of the region. Haimu, a 25-year-old khoomei (a local variant of overtone singing) singer, joined the troupe three years ago. Along with a six-member band, he performs fast songs and soft ones that he writesall while playing the horse-head fiddle.Although I learned the piano since childhood and grew up listening to various kinds of music, to me, the folk music of Inner Mongolia is the root, he says. Performing in remote villages is pleasant. I feel at home on the boundless grasslands, and the warm people there make me feel fulfilled. The first round of spring auction season in Beijing ended last week, but it failed to create much spring in the art market. Although two pieces of Chinese painting fetched more than 100 million yuan, the decline in trading volume and sale rate showed a downturn this year. In the “Grand View: Chinese Painting Highlight” session at China Guardian 2015 spring auctions, Pan Tianshous representative work Eagle, Rock and Flora hit a record auction price of 279 million yuan, while Li Kerans masterwork Jinggang Mountain fetched 126.5 million yuan, an unexpected high in recent years. However, the trading volume fells to 1.87 billion yuan from 2.22 billion yuan in the same period the year before. The Huangchen 2015 Spring Auctions, which recorded 42.5 million yuan in total sales, experienced the same. The section number went down to 5 from 12 compared to last year. According to expert Shao Jianwu, the art market did not attract much excitement this year due to the booming stock market and the persistent problems of forgery and fake deals. The two pieces of Chinese painting notched up high price this spring due to their own value not due to a revival in the market. The successful transaction of two works with a hammer price of more than 100 million yuan once again confirms that valuable and rare works of high quality always earn the long-lasting high price. Chinese painting and calligraphy is still the pillar of the market. However, the overall sales rate has dropped slightly, which reflects the demand for the ordinary auction goods has weakened,” said the president of China Guardians Hu Yanyan. Besides, the entry of new buyers also makes certain changes to the direction of purchasing. In a word, the overall market trend is very unpredictable. Although China Guardian 2015 Spring Auctions has achieved remarkable results, it does not mean that the market has walked out of the predicament. We still have to wait for the big economic boom to invigorate the art market.” Even so, the hot pursuit of some special items appeared this spring. A special session of China Guardian Spring Auctions titled “Fine GiltBronze Buddhist Images” achieved a great deal with total sales volume of 41.89 million yuan and 92 percent sale rate. The 5th Shamar Rinpoche Statue from 16-17th century of Tibet was sold for 5.06 million yuan. The Beijing Chengxuan Auctions featured almost 2,800 items of coins and stamps in three sessions with good sale rate. The Huachen Auctions also set a special session of photographs under the condition of large-scale decline of auction sessions. There was a palpable dull thud of disappointment that accompanied the return of the imperial entourage of Zhen Huan to her homeland. It followed a couple years of hushed excitement as Chinese fans were fed tidbits about their proud concubine who was supposed to conquer the high ground of the North American market. Zhen Huan is, of course, the title character of The Legend of Zhen Huan, a 2011 television series that swept China off its feet and later took other Asian countries by storm. Two years ago, it was reported that HBO, a premium cable service headquartered in the United States, was going to air it in North America after some modification. Now, a condensed version that provides English subtitles but no dubbing has finally been made available on Netflix for online streaming. This version, highly anticipated as a milestone in Chinas cultural foray overseas, has been widely panned by its home audience. Retitled Empresses in the Palace, the American version has been shortened from its original 76 episodes at 45 minutes each, to six 90-minute episodes. The quick pacing threw off many native viewers, who are accustomed to a more leisurely daytime-soap-style narrative rhythm. (Chinese TV stations would run two or three episodes every day.) I did not finish the full-length version and found the truncated one not difficult to follow. Whats lost, I believe, are the interesting setups and pauses that illuminate the Chinese art of storytelling. Much of the plot is still there. It is the flavor that was sacrificed. The American edition uses the framework of the Empress Dowager in her senior years reminiscing at the beginning and the end of each episode, hinting at whats to come and recapping the key points. This device, not used in the original, is culturally understandable but artistically mediocre. What puzzles me is the two new songs for the opening and end credits. They were written in English, but sung by Chinese with an uncomfortable accent. They were obviously designed to appeal to an English-speaking base, but do not jibe with the Chinese dialogue. Speaking of the dialogue, the English translation, picked apart by some Chinese, is too literal for my taste. I can imagine a typical American hit by a flurry of royal ranks, addresses and greetings, even multiple names and titles for the same person. The first half hour must be a swamp to wade through, very much like my experience of getting through a Tolstoy tome with its endless inflections of names transliterated into lengthy Chinese. I see the choice of verbatim translation as an effort for conveying exotica. It is fairly competent, with no error that I could detect, but fails to rise above words or capture the