CdTe/CdS异质结太阳电池的电特性--关于"CdTe/CdS异质结特性"一文同郭江等商榷

笔者认为郭江等关于“CdTe／CdS异质结特性”一文，对CdTe／CdS太阳电池的CdS／CdTe异质结特性的讨论时存在理论上的错误和设计思想不妥。例如，求解CdTe／CdS异质结空间电荷区电势满足的泊松方程时，所给的边界条件有错，因而所得的电势分布亦有错；关系式△Er=(Eg2-Eg1)-△Ec=0有错；CdTe／CdS异质结能带结构不妥等。据此，我们针对上述CdS／CdTe异质结太阳电池存在的问题进行了理论研究和讨论，所得到的相应研究结果，与郭江等商榷。     

CdTe/CdS异质结特性

从理论上对CdTe／CdS太阳电池CdS/CdTe异质结的特性进行了研究和讨论，结果表明可以简单利用改变CdTe、CdS两种半导体材料的掺杂浓度来改变CdS/CdTe异质结的能带结构。针对不同的能带结构采用了不同的物理模型，得到的CdS/CdTe异质结伏安特性曲线有一折点，且折点位置随异质结能带结构的变化而变化。     

CdS／CdTe－CdS／Cu_2S异质二重结薄膜太阳电池的设计与计算

根据半导体材料的性能参数，考虑光电压Ｖ和耗尽区宽度Ｗ的变化对光电流ＪＬ的影响，较严格地计算了ＣｄＳ／ＣｄＴｅ和ＣｄＳ／Ｃｕ２Ｓ两种异质结单晶薄膜太阳电池的光伏特性曲线。然后在的条件下，对由上述两种异质结构成的二重结太阳电池的ＣｄＴｅ、Ｃｕ２Ｓ厚度进行匹配，计算各种组合下二重结太阳电池的光伏特性曲线。理论证明最佳匹配厚度Ｈｍａｘ约为９．０６μｍ，最大短路电流、开路电压、转换效率分别为１４．２２ｍＡｃｍ－２、１．３Ｖ和１４、６８％。     

多晶CdS／Cu2S异质结太阳电池光电流及转换效率的计算

根据半导体材料的性能参数，对多晶ＣｄＳ／Ｃｕ２Ｓ薄膜太阳电池在各种浓度下的光伏特性作了较深入的分析和计算。计算中考虑到耗尽区宽度的变化以及内表面复合损失对光电流ＪＬ的影响，同时还用Ｒｏｔｗａｒｆ晶界复合损失模型计算了晶粒度对光电流及光伏特性的影响。存在一个最佳Ｃｕ２Ｓ受主浓度Ｎａ＝１０＾１５ｃｍ＾－３，单晶和晶粒度Ｒ＝３μｍ的多晶电池，其转换效率分别为１３．６％和１３．３％。     

光注入提升晶体硅异质结太阳电池性能的研究

该文制备工业尺寸的晶体硅异质结太阳电池,研究光注入对电池光电性能的影响。实验结果表明：光注入有效提升了晶体硅异质结太阳电池的光电转换效率,经过光注入后电池光电转换绝对效率提升了0.33%,均值达到24.47个百分点。对比光注入前后的光电性能参数,其效率提升的主要因素是光注入使得电池的填充因子被有效提升。结合光注入前后电池的Suns-V_oc测试,证实了光注入能使电池的串联电阻大比例降低。因此,光注入改善电池性能的主要物理原因可归结为：串联电阻的降低提升了电池的填充因子。     

产业化晶硅太阳电池串联电阻研究

详细研究了产业化晶硅太阳电池生产中,电池正面电极体电阻、发射极横向电阻,以及正面电极与发射极结区金/半接触电阻对晶硅太阳电池串联电阻的具体影响。通过实验,文章给出了一种既经济又能有效降低电池串联电阻、提升晶硅太阳电池光电转换效率的优化方法。     

CdS/CdTe太阳电池中CdS多晶薄膜的结构和光学性能

采用XRD,AFM,XPS和光学透射谱对化学水浴法制备的CdS多晶薄膜进行了测试分析。刚沉积的CdS多晶薄膜均匀、透明、致密,主要呈现立方结构;Cd和S的原子百分比约为1 10;能隙(Eg)约为2 47eV。在不同温度下后处理会出现六方结构和3CdSO4·8H2O衍射峰,同时晶面择优取向发生了变化。通过沉积高质量的CdS薄膜,获得了效率约13 4%的CdS/CdTe小面积太阳电池。     

硅基异质结太阳电池的研究现状与前景

简要介绍了当前低成本太阳电池的现状,对硅基异质结太阳电池的构成进行简要分析,筒述了如HIT、a—C／c—Si、a—C／C60／c—Si以及nc—Si／mc—Si等几种高效硅基异质结太阳电池的研究,并介绍了太阳模拟软件对硅基异质结电池工艺参数的模拟结果。最后介绍了Si／Ge／Si双异质结太阳电池的制备技术,并对基于硅基异质结高效低成本太阳电池的发展进行展望。     

CuPc-G-PAn/Perylenes异质结太阳电池性能研究

对聚苯胺材料进行染料接枝改性,将其用作异质结光伏电池的p型材料,制作出结构为导。电玻璃／酞菁铜接枝聚苯胺（p型）／Pei（n型）／Al）简写为ITO／CuPc-G-PAn(p型）／Pei（n型）／A1)的有机p-n异质结光伏电池。该电池在37．2W／m^2的碘钨灯照射下,开路电压Voc=802mV,短路电流I=41μＡ／cm^2,填充因子FF＝58％,能量转换效率大约为0．51％,它比聚苯胺及Pei肖特基电池大得多。通过测量其电流－电压J－V和电容－电压C－V特性,研究了其光伏效应及电学性能。J－V特性表明,二极管的曲线因子约为6．3,比1大得多;C－V特性表明,在CuPc-G-PAn／Pei界面处的耗尽层约为231nm,从p/n层的光吸收谱可知,光激活层在CuPc-G-PAn／Pei界面处,它们分别与ITO及铝形成欧姆接触,对在暗场及光照下电荷传输机理作了较详细的分析。     

晶体硅太阳电池串联内阻的函数形式

在已知的四种电阻函数形式中，通过理论推导并结合晶体硅太阳电池功率随着温度上升而下降的实验事实，理论证明晶体硅太阳电池串联内阻具有正温度系数半导体型电阻的数学表述形式。利用该数学形式对实测内阻数据进行拟合，结果令人满意。     

THE INFLUENCE OF DEPOSITION AND PROCESSING CONDITIONS ON THE PROPERTIES OF EVAPORATED CdTe/ CdS LAYERS AND SOLAR CELLS

The influence of the deposition and CdCl₂ doping conditions on the properties of CdTe layers and on the performance of CdTe/CdS/ITO/glass solar cells is reported. Relatively high deposition temperatures (300-350°C) were found to enhance the reproducibility of the optical quality of the CdTe. Oxidation of CdTe layers during air annealing was observed and monitored by XRD. Conventional wet dip and CdCl₂ vapour doping of CdTe are compared. Methods for reducing the incidence of pinholes in the CdTe are described, the junction uniformity having been monitored by EBIC. The best solar cell made in this work had an efficiency of 9.87%. (V _oc = 0.696V, J _sc = 24.1 mA/cm², FF = 59%).     

太阳电池效率与串联电阻的近似指数关系

太阳电池的串联电阻对其效率有显著的影响。呈近似指数关系。串联电阻对填充因子有重要的影响。串联电阻。对太阳电池的卜一v特性进行数值分析，证明效率和串联电阻由实测的开路电压、短路电流和效率可以简便地数值计算确定     

一种聚合物/C60异质结有机太阳电池

用MEH-PPV为给体(空穴传输)、C60为受体(电子传输)首先制备了分层和体异质结结构的两种器件,器件结构为ITO/PEDOT:PSS/MEH-PPV/C60/Al和ITO/PEDOT:PSS/MEH-PPV:C60/Al。之后又制备了结构为ITO/PE-DOT:PSS/MEH-PPV:C60/C60/Al的第3个器件。作者比较了这3种器件的光伏性质,发现器件3的短路电流密度(JSC)比器件1和器件2的分别增加了300%和150%,开路电压(VOC)分别增加了100%和20%。这主要是由于C60层增加了电子由受体传输到负电极的通道并增大了给体受体界面面积。另一原因是此C60层一定程度地阻挡了空穴从有机物向负极的传输,从而有效地改善了太阳电池的性能。     

CdTe/CdS Solar cells on flexible molybdenum substrates

Development of CdTe/CdS solar cells on flexible metallic substrates is highly interesting due to the light weight and flexible nature of the solar modules. We have deposited CdTe films onto flexible molybdenum substrates using close-spaced sublimation technique and the CdTe/CdS junction was developed by depositing a thin layer of CdS onto the CdTe substrate from a chemical bath. The devices were characterized by Current–voltage (I–V) and photocurrent spectroscopy techniques. Prior to the deposition of the transparent conducting layer, the devices were annealed in air at different temperatures and found that the devices annealed at 400°C have better photovoltaic parameters. The efficiency of a typical device under 60 mW cm⁻² illumination was estimated as 3.5%.     

EFFECT OF OXYGEN ON PHOTOVOLTAIC PROPERTIES OF SCREEN-PRINTED CdS/CdTe SOLAR CELL AND MODULE Module Reliability and Oxygen Deficiency

An n-CdS/p-CdTe solar cell module constructed by complete seal of solar cell formed on a glass substrate by screen-printing and sintering process, was subjected to a heavy sunshine weather-meter test. The conversion efficiency of the module began to degrade after 50 days. Chemical analyses on gases in the sealed module showed that decrease in oxygen down to 2 vol.% had caused the degradation. Inversely, when sufficient oxygen was supplied to the solar cell by breaking the seal, the efficiency recovered up to its initial value within several days even at room temperature. Estimation of reaction velocity at room temperature suggested that the present recovery phenomenon was the same as increase in p-type characteristics by heat treatment in air in other fabrication process of CdS/CdTe junction. Easiness and reversibility of transformation from oxygen deficient to sufficient states in CdTe, strongly suggest that oxygen in CdTe induces a single acceptor which was confirmed in oxygen doped ZnSe.     

Device performance characterization and junction mechanisms in CdTe/CdS solar cells

The performance of CdTe/CdS solar cells has been successfully characterized in terms of a device model based on Shockley–Read–Hall (SRH) recombination theory. The model has been applied to a large number of devices from our laboratory in the 10–15% efficiency range and is able to provide key insights into the diode properties of our devices and the fundamental mechanisms that determine performance. Methods for the reliable measurement of key device parameters are presented, and the results are verified by simulating the characterization data in a self-consistent manner. Crossover between the dark and light J–V curves has been identified as a front contact phenomenon arising from the presence of CdS. Junction mechanisms and an observed relationship between reverse saturation current and diode quality factor are discussed. Our techniques indicate that all values of diode quality factor are between 1 and 2 which is consistent with SRH recombination theory and explainable in terms of the location and lifetimes of the recombination centers. It is found that devices with large diode factors are dominated by midgap states. Reduction of midgap states results in a reduction of the diode factor and improved performance.