Exploring the potential for high-quality epitaxial CdTe solar cells
Exploring the potential for high-quality epitaxial CdTe solar cells
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DOI：
10.1109/pvsc.2014.6925414
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
Tao Song;A. Kanevce;J. Sites
中科院分区：
文献类型：
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作者：
Tao Song;A. Kanevce;J. Sites
Traditional polycrystalline CdTe solar cell performance is limited by recombination at the grain boundaries, low carrier density (p), compensation from impurities, and a low minority carrier lifetime (τ). The maximum values for these critical parameters in polycrystalling devices are p 15 cm-3 and τ ~ 10 ns with open-circuit voltage (VOC) ~ 900 mV and η ~ 20%. Epitaxial CdTe with high-quality, low defect-density, and high carrier density, could yield a higher-efficiency PV device. Using numerical simulation, we investigate the combined effects of minority carrier lifetime τ (0.1 - 500 ns) and carrier density p (1×1014 - 5×1018 cm-3) on device performance, predicting obtainable performance of VOC > 1100 mV and η > 25% for high τ and high p. While the VOC is strongly affected by both p and τ, the short-circuit current (JSC) is mainly dependent on the lifetime τ and absorption losses in the front contact stack. In addition, increasing the thickness of p-CdTe (varied from 0.5 - 20 μm) at different τ (1 - 100 ns) shows an improvement in JSC due to increased long-wavelength photon collection and then saturates for thicker p-CdTe. In some cases, the cell performance is compromised by the presence of a significant back-contact barrier Φb. The simulated results show that the cell performance is not strongly affected until Φb exceeds 0.4 eV.
