SOME FABRICATION PROCEDURES FOR ELECTRODEPOSITED CdTe SOLAR CELLS

Solar cells with a nCdS/pCdTe heterojunction have been fabricated from elcctrodepositcd CdS and CdTe layers. Sets of cells were made with CdTe films deposited at a range of potentials (QRP) from solutions in which the concentrations of cadmium and of tellurium ions were systematically varied. The properties of the CdTe films and of the cells were examined. The range of values over which suitable solar cells could be made was determined for a given set of processing conditions. The most efficient solar cells were obtained under those processing conditions for solutions with cadmium ion 2.5 M and tellurium ions 120 ppm deposited in a range of QRP's of 20—40 mV (relative to a saturated calomel reference electrode). Morphological studies showed that the most efficient cells had (he largest grain size. Electrical and capacitance measurements showed that the major losses in the solar cell parameters increased with increased polycrystalline structure.     

影响SSP衬底上多晶硅薄膜太阳电池效率的因素

该文分析了颗粒硅带(SSP;Silicon Sheet from Powder)衬底的杂质、缺陷和晶粒尺寸以及电池的电极设计对多晶硅薄膜太阳电池效率的影响;报道了用快速热化学汽相沉积法(RTCVD)在SSP上制备多晶硅薄膜电池的结果;得到电池的开路电压为506.8mV,短路电流为26.69mA,转换效率为8.25%(AM1.5,24℃,Area=1tm2).     

J-CHART METHOD IN DESIGNING A PARTIALLY SOLAR HEATED DRYER

A new chart of simulation method, named J-chart, has been developed for predicting the long-term average performance of solar drying systems. The result of many simulations allows to develop a simple graphical method, represented by 3 charts and their polynomial correlations, to obtain a general design procedure for a partially solar heated dryer. The first one is the drying time, the second one is the fraction of heating load supplied by solar energy and the third one is the fraction of economized energy. These charts and the correlations are used in establishing relationships between the collector area and the weight of the produce to be dried or the dried produce. This method is developed by using the monthly average values for a moderate climate (Perpignan, Φ = 42.41^°) and with the assumption that the dryer is used daily over a year and the duration of drying operation is assumed to be less than 24 hours.     

多晶硅薄膜太阳电池厚度和晶粒尺寸对其性能的影响

利用PC1D计算了结构为n^ /p小和n^ /p—p^ 多晶硅薄膜太阳电他的品粒尺寸和薄膜厚度对其Voc，Jsc和η的影响。计算结果表明：对无陷光结构的多晶硅薄膜太阳电池，要获得10％的效率，薄膜厚度至少应大于22μm；晶粒尺寸大于薄膜厚度的4倍时，晶界复合对载流子寿命的影响可以忽略；同时表明：太阳电他的背表面场(BSF)对提高多晶硅薄膜太阳电他的性能具有很大的作用。     

开口隔离层上多晶硅薄膜制备

在SSP硅带衬底上制备开口SiO2隔离层,在隔离层上沉积多晶硅薄膜籽晶层;然后以ZMR将制备的多晶硅薄膜区融、进行再结晶,制备了SSP隔离层上多晶硅薄膜,并制备了多晶硅薄膜电池。研究结果表明:ZMR对籽晶层的区融、结晶效果比较理想,晶粒尺寸增大到厘米级长、毫米级宽;经过晶硅薄膜沉积后,开口隔离层的孔洞未完全被多晶硅薄膜层覆盖住;制备的电池的光特性参数Voc、Isc、FF都比较低,电池的最高转换效率为3.83%;指出了改进的工艺措施。     

SOI材料上硅薄膜电池的研究

用注氧隔离法在单晶硅衬底中形成SiO2隔离层,制备成SOI(SiliconOnInsulator)衬底,用快速化学汽相沉积(RTCVD)法在此衬底上制备硅薄膜,热扩散形成PN结,制备成薄膜太阳电池,电池表面钝化及减反膜采用的是等离子增强化学气相沉积(PECVD)方法制备的SiN,薄膜电池的电极全部由正面引出,制成的23μm厚薄膜电池的光电转换效率为8 12%(1×1cm2,AM1 5,23℃)。扩展电阻的测量表明电池有良好的PN结特性;量子效率测量表明SiN比常规的热氧化SiO2有更好的减反射和钝化作用;电池的暗特性表明电池具有较高的串联电阻,并分析了正面引电极对串联电阻的影响。     

低温沉积硅薄膜电池及其在塑料衬底上的应用

采用射频等离子体增强化学气相沉积(RF-PECVD)技术,保持衬底温度在125℃沉积硅薄膜材料及电池,研究了硅烷浓度、辉光功率等沉积参数对材料和电池性能的影响。在125℃的低温条件下,通过优化沉积工艺,在玻璃衬底和PET塑料衬底上分别制备出效率达到6.8%和3.9%的单结非晶硅电池。在PET衬底上,将低温沉积非晶硅电池的技术应用于的叠层电池的顶电池,制备出效率为4.6%的非晶/微晶硅叠层电池。     

外延晶体硅薄膜电池的EBIC与SR-LBIC特性分析

电子束诱导电流(EBICElectron Beam Induced Current)是研究晶体缺陷(如晶界、位错、沉淀等)复合特性的一种有力工具.该文对以颗粒硅带为衬底的晶体硅薄膜电池表面及电池截面的晶体缺陷、特别是对晶界的复合行为进行了研究.电池表面EBIC照片表明复合中心位于晶界处,在小颗粒集中区域复合越强.截面的EBIC结果表明在颗粒晶界处分别有着强弱复合,与晶界处强的复合行为相比,颗粒内部没有或仅有比较弱的复合行为发生.靠近电池表面处的颗粒晶界和颗粒内部复合行为由于H钝化得到减弱,少数载流子扩散长度随深度的增加而降低.光谱决定的光束诱导电流(SR-LBIC)表明扩散长度在整个电池表面是不均匀的,最大扩散长度与外延层厚度相当.     

Na掺入制备不锈钢衬底CIGS太阳电池

以轻质柔性不锈钢材料为衬底,利用共蒸发法制备较高质量的四元化合物Cu(In,Ga)Se2薄膜,在沉积CIGS薄膜前沉积一定厚度的NaF预置层,使得所制备的CIGS薄膜含有适量浓度的Na,并获得了10.06%的转换效率.利用X射线衍射仪和X射线荧光光谱仪分别测量了所制备薄膜的晶相和组分,利用扫描电子显微镜分析了不锈钢衬底CIGS太阳电池的断面形貌,最后分析了NaF的掺入对CIGS太阳电池的影响.     

A STUDY OF EFFICIENCY LIMITING DEFECTS IN POLYCRYSTALLINE CdTe/CdS SOLAR CELLS

Efficiency limiting mechanisms associated with CdS substrates, CdCl2 treated CdTe films, and Cu/Au contacts were investigated. It was found that heat treatment of CdS in hydrogen ambient prior to CdTe deposition removed the oxygen related defects from the CdS films, but created Cd deficient CdS surface, resulting in an optimum temperature of 450°C. Growth of CdTe films on the CdS under Te-rich conditions enhanced the interdiffusion between CdTe and CdS and reduced the CdTe bandgap to 1.47eV, whereas, growth of CdTe films under Cd-rich conditions retained the CdTe bandgap at 1.5 eV. CdCl2 treatment on CdTe improved the cell performance significantly by virtue of grain growth, reduced leakage current, and change in carrier transport mechanism. However, it also produced defects at Eν + 0.64 and Eν + 0.17 eV due to VCd-Cl complexes. An inverse correlation was found between the density of these defects and V ∞ Finally, a rapid initial degradation was observed in the higher efficiency (10-12%) CdTe cells with Cu/Au contacts but a bromine-methanol etch was found to restore the cell performance.     

颗粒硅带多晶硅薄膜太阳电池的研制

以工业硅粉为原料制备出颗粒硅带（SSP），对颗粒硅带表面形态进行了分析。以SSP为衬底，采用快速热化学气相沉积（RTCVD）法生长多晶硅薄膜，并以此制作出效率为2．93％的颗粒硅带多晶硅薄膜太阳电池，这在国内属首先。并报道了对以SSP为衬底的多晶硅薄膜太阳电池的初步研究结果，同时讨论了该类电源的结构、工艺特点和改进措施。     

ELECTRODEPOSITED CdTe FOR THIN FILM SOLAR CELLS

Large area 300 mm x 300 mm CdS/CdTe solar cells with record efficiencies over 10% have been fabricated using a reproducible, safe and low cost electrodeposition route for CdTe deposition. CdS window layers have been grown using chemical bath deposition which produces uniform adherent films by a cost effective route. Electrical characterization of small area (0.02 cm²) devices confirms that the structure is p-n rather than p-i-n. Module reliability tests show efficiency stability for more than 16,000 hours outside, and very little change using indoor environmental tests.     

柔性不锈钢衬底CIGS薄膜太阳电池

以轻质柔性不锈钢材料为衬底,利用三步共蒸发法制备较高质量的四元化合物Cu(In,Ga)Se_2薄膜,CIGS层在Mo导电层上具有很强的附着力。利用XRD和XRF分别分析了所制备薄膜的晶相和组分。以ZnO:Al/i-ZnO/ CdS/CIGS/Mo/Stainless steel结构为基础得到最高转换效率为9.39%的柔性太阳电池。最后讨论了衬底粗糙度、有害杂质的扩散和不含有Na元素等不利因素对于电池性能的影响。     

GROWTH OF HETEROEPITAXIAL CdTe LAYERS ON REUSABLE Si SUBSTRATES AND A LIFT-OFF TECHNIQUE FOR THIN FILM SOLAR CELL FABRICATION

Heteroepitaxial (111) and (100) oriented CdTe layers have been grown on Si substrates by conventional molecular beam epitaxy (MBE) and photo-assisted MBE (PAMBE) using stacked BaF₂-CaF₂ as a buffer to overcome the 19% lattice mismatch between Si and CdTe. Heteroepitaxial As doped p-type CdTe(lOO) layers have been grown on BaF₂-CaF₂/Si(100). The dopant activation is accomplished using an extra Cd source and laser illumination of the substrate during growth. The growth kinetics and surface reconstructions have been studied using RHEED during CdTe growth under different conditions, and the induced effects on Te-desorption, Cd-migration, and As-substitution on Te-vacancy site have been correlated. The resistivity of As doped CdTe layers is down to 20 ohm cm. The 8 K photoluminescence spectra of such a layer shows a dominant (A^°, X) peak at 1.590 eV and the As acceptor level corresponds to a shallow level with = 60 me V activation energy. A lift-off technique has been used to separate the single crystal CdTe thin films from the Si wafer by dissolving the fluoride buffer. CdS/CdTe solar cells have been fabricated in these layers.     

化学水浴沉积CIGS太阳电池缓冲层ZnS薄膜的研究

在含有ZnSO4、SC(NH2)2、NH4OH的水溶液中采用CBD法沉积ZnS薄膜,研究了沉积时间、水浴温度、搅拌等工艺条件对沉积薄膜的影响。薄膜的厚度与搅拌的强度有很大关系,表明扩散传质是薄膜生长的控制步骤。XRF和XRD测试表明沉积的薄膜中含有ZnS和Zn(OH)2,SEM测试表明薄膜颗粒大小相近,但不致密。随着沉积时间的增加,薄膜厚度增加,透过率减小。当前采用CBD-ZnS薄膜制备的无镉CIGS太阳电池转换效率达到8.54%。     

颗粒硅带为衬底的多晶硅薄膜太阳电池制备工艺

主要阐述了以低纯度颗粒硅带(SSP—Silicon Sheet from Powder)为衬底的多晶硅薄膜(poly-CSiTF)太阳电池的制备，给出制得的太阳电池I—V曲线和光谱响应曲线并由此讨论影响电池性能的可能因素，着重分析了颗粒硅带衬底的作用。目前，在没有任何电池工艺优化的条件下，在低纯度硅带上制得多晶硅薄膜电池的转换效率通常在5％～7％范围(电池面积1cm^2)。     

柔性衬底微晶硅薄膜太阳电池研究

采用等离子增强化学气相沉积(PECVD)技术制备了系列本征微晶硅薄膜材料和nip单结微晶硅太阳电池,研究了硅烷浓度、衬底温度和辉光功率等沉积参数与薄膜材料性能、薄膜电池性能三者之间的关系.拉曼光谱和器件测试结果表明:随硅烷浓度的增加,本征层晶化率逐渐减小,直至转变为非晶硅;沉积温度高于200℃时,电池性能严重恶化;随等离子辉光功率增加,材料晶化率保持不变,而电池开路电压逐渐增大,短波光谱响应逐渐增强.在此基础上,优化了单结微晶硅电池沉积参数,得到效率为6.48％ (AM0,25℃)的单结微晶硅薄膜太阳电池;并将其应用到非晶硅／微晶硅叠层电池中,在不锈钢柔性衬底上得到效率为9.28％( AM0,25℃)的叠层电池.     

多晶硅薄膜太阳电池的研究与进展

从薄膜的沉积方式和沉积温度以及衬底材料等几方面综合分析了多晶硅薄膜制备工艺的特点及多晶硅薄膜太阳电池的最新研究进展。并以颗粒硅带(SSP)为衬底，采用快热化学气相沉积(RTCVD)法制备了多晶硅薄膜，随后制得的多晶硅薄膜太阳电池的效率达到6．05％。     

SOME PHENOMENA IN CdTe/CdS THIN FILM SOLAR CELLS MADE BY CLOSE-SPACED SUBLIMATION

CdTe/CdS heterojunction thin film solar cells of 11.7% efficiency have been made by close-spaced sublimation of CdTe. Some results regarding the influence of the CdCI₂ treatment and contacting are given stressing the requirement of more in-depth analysis of the CdTe cells made by different processes in order to understand the common and basic mechanisms better.     

硅太阳电池稳步走向薄膜化

考察了硅太阳电池在光伏产业中所处的地位,分析了薄膜硅太阳电池的发展趋势。指出硅太阳电池在未来15a仍将保持优势地位,并继续沿着晶硅电池和薄膜硅电池两个方向发展。在此发展过程中,两个发展方向的主流很可能会汇合到一起,共同促使低成本、高效率、高可靠薄膜晶硅电池的诞生和产业化,从而继续保持硅太阳电池的优势地位。