Characterization of damp heat degradation of CuInGaSe2 solar cell components and devices by (electrochemical) impedance spectroscopy
Characterization of damp heat degradation of CuInGaSe2 solar cell components and devices by (electrochemical) impedance spectroscopy
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DOI：
10.1117/12.895918
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发表时间：
2011-09
期刊：
影响因子：
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通讯作者：
F. Pern;R. Noufi
中科院分区：
文献类型：
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作者：
F. Pern;R. Noufi
这项工作评估了（电化学）阻抗谱（IS，或ECIS）监测接触材料、CuInGaSe2 （CIGS）太阳能电池组件和器件的湿热（DH）稳定性的能力。用ECIS检测了CIGS器件的细胞特性及其变化。分别制备裸样品组和封装样品组，并在85°C和85%相对湿度（RH）的环境室中暴露。裸露样品暴露在DH 50-100小时内测试的ECIS结果允许确定使用导电银膏和低熔点焊料合金与金线进行DH稳定的外部连接。裸露的Mo和AlNi栅格迅速退化（腐蚀），而Ni栅格是h稳定的。湿阻尼al掺杂ZnO （AZO）和双层ZnO （BZO）可能在DH作用下发生了水解“电容器形成”反应，导致ECIS中具有非常高电阻的“瞬态”行为，这是四点探针无法检测到的。使用允许水分进入控制的封装测试结构，DH诱导的玻璃上BZO的降解（电阻增加）率从使用透湿的Tedlar/聚酯/Tedlar （TPT）背板的0.21欧姆/小时降低到使用防潮的gf -200薄膜的1.0 x 10-3欧姆/小时，而玻璃上的Mo在暴露超过1270小时后没有表现出与裸样品相同的导电降解和腐蚀。用TPT背板封装的CIGS太阳能电池在774小时的DH暴露下不规则退化。通过阻抗数据的曲线拟合提取的关键电阻和电容参数清晰地显示了DH暴露对电池特性的变化和影响。“p-n结电容器”明显受到DH的严重“抑制”或短路。ECIS结果显示与太阳能电池的电流电压（I-V）退化趋势相当好地相关。此外，ECIS分析能够区分由“结电容器”短路、损坏或击穿引起的电池降解与由AlNi/BZO层上的导电故障引起的电池降解。
This work evaluated the capability of (electrochemical) impedance spectroscopy (IS, or ECIS as used here) to monitor damp heat (DH) stability of contact materials, CuInGaSe2 (CIGS) solar cell components, and devices. Cell characteristics and its variation of the CIGS devices were also examined by the ECIS. Bare and encapsulated sample sets were separately prepared and exposed in an environmental chamber at 85°C and 85% relative humidity (RH). The ECIS results from bare samples tested within 50-100 h of DH exposure allowed the determination of the use of a conducting Ag paste and a low-melting-point solder alloy for making a DH-stable external connection with Au wires. Bare Mo and AlNi grid degraded (corroded) rapidly while Ni was DH-stable. The moisture-dampened Al-doped ZnO (AZO) and bilayer ZnO (BZO) likely underwent hydrolytic "capacitor-forming" reaction by DH, resulting in "transient" behavior of very high resistance in ECIS that was not detected by four-point probe. Using an encapsulation test structure that allowed moisture ingress control, DH-induced degradation (resistance increase) rates of BZO on glass decreased from 0.21 ohm/h using a moisture-permeable Tedlar/Polyester/Tedlar (TPT) backsheet to 1.0 x 10-3 ohm/h using a moisture barrier FG-200 film, while Mo on glass did not exhibit the same conducting degradation and corrosion as the bare samples after over 1270 h DH exposure. CIGS solar cells encapsulated with a TPT backsheet degraded irregularly over 774 h DH exposure. Key resistance and capacitance parameters extracted by curve fitting of impedance data clearly showed the variation and impact of DH exposure on cell characteristics. Profound "depression" or shorting of the "p-n junction capacitor" by DH was evident. ECIS results are shown to correlate reasonably well with the solar cells' currentvoltage (I-V) degrading trends. Furthermore, ECIS analysis was capable of differentiating cell degradation due to "junction capacitor" shorting, damage or breakdown from that due to electrical conduction failure on AlNi/BZO layers.