Modification of electron states in CdTe absorber due to a buffer layer in CdTe/CdS solar cells
Modification of electron states in CdTe absorber due to a buffer layer in CdTe/CdS solar cells
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DOI：
10.1063/1.4934680
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发表时间：
2015-06
影响因子：
3.2
通讯作者：
Y. Fedorenko;J. Major;A. Pressman;L. Phillips;K. Durose
中科院分区：
文献类型：
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作者：
Y. Fedorenko;J. Major;A. Pressman;L. Phillips;K. Durose
通过应用交流导纳谱方法，缺陷态的能量分布确定在碲化镉纳入薄膜太阳能电池结构上的ZnO，ZnSe，和ZnS缓冲层的结论。结合Mott-Schottky分析，结果显示了受缓冲层选择影响的缺陷态密度和未补偿受主浓度的强烈修改。在ZnSe和ZnS上形成的太阳能电池中，观察到费米能级和占主导地位的深陷阱能级的能量位置向CdTe的中间带隙移动，这表明中间带隙态可能充当复合中心并影响太阳能电池的开路电压和填充因子。对于更深的状态，观察到的增宽参数增加，表示在微观尺度上的电荷的波动。这种变化可以归因于晶界应变和在多晶碲化镉的晶界界面态处捕获的电荷的修改。
By application of the ac admittance spectroscopy method, the defect state energy distributions were determined in CdTe incorporated in thin film solar cell structures concluded on ZnO, ZnSe, and ZnS buffer layers. Together with the Mott-Schottky analysis, the results revealed a strong modification of the defect density of states and the concentration of the uncompensated acceptors as influenced by the choice of the buffer layer. In the solar cells formed on ZnSe and ZnS, the Fermi level and the energy position of the dominant deep trap levels were observed to shift closer to the midgap of CdTe, suggesting the mid-gap states may act as recombination centers and impact the open-circuit voltage and the fill factor of the solar cells. For the deeper states, the broadening parameter was observed to increase, indicating fluctuations of the charge on a microscopic scale. Such changes can be attributed to the grain-boundary strain and the modification of the charge trapped at the grain-boundary interface states in polycrystalline CdTe.