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。     

Photovoltaic materials, past, present, future

This paper traces briefly the history of this photovoltaic materials and it tries to look at possible future scenarios. A large part of the paper is concerned with silicon although from solid-state physics we know that silicon is not the ideal material for photovoltaic conversion. From the first solar cell developed at Bell Laboratories in 1954 photovoltaics was dominated by silicon. The reasons for this dominating position are investigated. Crystalline silicon today has a market share of 86% which is almost equally distributed between single crystal and cast silicon. Amorphous silicon has another 13%. The main endeavor is to reduce cost. Present trends in the crystalline field are reviewed. The conventional technology still has significant potential for cost reduction but this comes only with increasing volume. A problem to be solved is the supply of solar-grade silicon material. Other future possibilities include thin film crystalline silicon on different substrates. Because of the low absorption coefficient of silicon light trapping is required. True thin film materials need only 1–2 μm of material. Amorphous silicon, copper indium diselenide (CIS) and CdTe are hopeful approaches for very cost-effective solar cells. Some other, more speculative materials and concepts are described at the end of this paper     

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%。     

CIGS电池缓冲层CdS的制备工艺及物理性能

在含有醋酸镉、醋酸氨、硫脲和氨水的水溶液中,化学沉积CdS半导体薄膜,薄膜的厚度与搅拌强度有很大关系,表明薄膜的生长速度是由OH-和SC(NH2)2的扩散传质为控制步骤。CdS薄膜的电阻率在104~105Ω.cm之间。CdS薄膜的晶格在乙酸胺浓度较小时,为六方晶和立方晶混合结构;乙酸胺浓度较大时,为立方晶结构。利用六方晶与立方晶混合的CdS制备的CIGS太阳电池,光电转换效率最大可达12.1%,3.5×3.6cm2小面积组件为6.6%。立方相CdS制备的最佳电池效率达到12.17%。两种晶相结构的CdS薄膜对CIGS太阳电池的性能影响没有明显的差别。     

太阳能电池研究的新进展

简要回顾了第一代晶体硅和第二代薄膜太阳能电池的发展状况,并介绍了基于薄膜技术的第三代高性能太阳能电池的基本原理和发展趋势。     

电沉积法制备铜锌锡硫薄膜概述

Cu_2ZnSnS_4(CZTS)为锡黄锡矿结构的四元化合物,其禁带宽度为1.45 e V,与半导体太阳能电池所要求的最佳禁带宽度(1.5 eV)十分接近;该材料与目前在薄膜太阳能电池领域表现出色的黄铜矿结构的CIGS(铜铟镓硒)材料具有相似的晶体结构,且CZTS有着很好的光电性能,组成元素在地球上含量丰富,安全无毒和环境友好,因而成为太阳能电池吸收层的最佳候选材料之一。介绍了Cu_2ZnSnS_4(CZTS)薄膜材料的结构特性和光学特性,总结了电化学沉积方法制备CZTS的研究现状。最后对CZTS目前存在的挑战和今后的研究重点进行总结并展望了将来可能的突破方向。     

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)。     

Schottky solar cells with amorphous carbon nitride thin films prepared by ion beam sputtering technique

This paper reports on the successful deposition of amorphous carbon nitride thin films (a-CN_x) and fabrication of ITO/a-CN_x/Al Schottky thin-film solar cells by using the technique of ion beam sputtering. XPS and Raman spectra are used to characterize the deposited thin films. Nitrogen atoms are incorporated into the films in the form of carbon–nitrogen multiple bands. Their optical properties are also investigated using a spectroscopic ellipsometer and UV/VIS/NIR spectrophotometer. The refraction of the carbon nitride thin films deposited lies in the range of 1.7–2.1. The Tauc optical band gap is about 0.6 eV. The photovoltaic values of the device, short-circuit current and open-circuit voltage are 1.56 μA/cm² and 250 mV, respectively, when exposed to AM1.5 illumination (100 mW/cm², 25°C).     

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。     

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。     

New silicon thin-film technology associated with original DC-DC converter: An economic alternative way to improve photovoltaic systems efficiencies

In this article, we aim at optimizing an innovative tandem structure based on polymorphous and microcrystalline silicon for the top and bottom elementary cells, respectively, combined with an original DC-DC converter.The studied tandem structure is composed of two cells, each being connected to its own separate electrodes making the structure electrically decoupled but optically coupled. In those conditions, the constraint of current matching usually needed in the classical micromorph structures is avoided. As a result, the robustness against the current variations is enhanced and the efficiency of the structure is improved.Since the top cell plays the main role in the determination of the transmitted part of the incoming flux to the bottom cell, the thickness of the intrinsic layer of the polymorphous cell is tuned so that the output power of the global structure becomes maximal.To implement the electric decoupling of two sub cells, the studied structure needs two static converters. In order to minimize the converters bulk, we design an innovative output electric architecture and its optimized related control signals.     

Amorphous silicon solar cells

The perfectioning of the deposition techniques of amorphous silicon over large areas, in particular film homogeneity and the reproducibility of the electro-optical characteristics, has allowed a more accurate study of the most intriguing bane of this material: the degradation under sun-light illumination. Optical band-gap and film thickness engineering have enabled device efficiency to stabilize with only a 10–15% loss in the as-deposited device efficiency. More sophisticated computer simulations of the device have also strongly contributed to achieve the highest stable efficiencies in the case of multijunction devices. Novel use of nanocrystalline thin films offers new possibilities of high efficiency and stability. Short term goals of great economical impact can be achieved by the amorphous silicon/crystalline silicon heterojunction. A review is made of the most innovative achievements in amorphous silicon solar cell design and material engineering.     

密堆积升华制备碲化镉多晶薄膜

用密堆积升华法在３０－２００（×１３３．３）Ｐａ低压氦气、氩气等气氛下淀积多晶碲化镉薄膜。在硫化镉衬底上得到（１１１）面择优的碲化镉，晶粒尺寸４－８μｍ，厚度３－５μｍ。膜生长速率与总压力成反比，与气氛导热系数成反比。在１：４的３０（×１３３．３）Ｐａ氦气－氧气中，碲化镉的生产速率在１－１．５μｍｍｉｎ＾－１范围内。淀积过程是扩散控制。     

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。