In this work, the influence of the Ohmic-contact behavior at the absorber/transparent back-contact interface on the stability of flexible bifacial Cu(In,Ga)Se₂ (CIGSe) solar cells is investigated. In the case of the CIGSe/In₂O₃:SnO₂ (ITO) interface, the Ohmic contact is maintained via the introduction of trap-assisted recombination at the CIGSe surface during the ITO deposition. Post-annealed CIGSe/ITO interfaces are studied via time-resolved photoluminescence (TRPL). It is found that the TRPL lifetime of all the samples investigated drastically decreases after the ITO deposition owing to sputtering damage, whereas the TRPL lifetime tends to increase after heat treatment at 160 °C. This increase is attributed to the partial recovery of the sputtering damage during annealing; the increase is larger in samples with less severe sputtering damage than in samples with more severe sputtering damage. Flexible bifacial solar cells with Ohmic-like contact at the CIGSe/ITO interface show superior performance and long-term stability compared with those with non-Ohmic contact at the interface, which may be correlated with the alteration of the metastability during the ITO deposition and/or partial recovery of the sputtering damage. The best flexible bifacial CIGSe solar cells with Ohmic-like back contact show stable performance for over 70 days with efficiencies of 11.1% and 3.0% for the frontside and backside illuminations, respectively.

中文翻译：

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欧姆背接触对Cu(In,Ga)Se2基柔性双面太阳能电池稳定性的影响

在这项工作中，研究了吸收体/透明背接触界面处的欧姆接触行为对柔性双面 Cu(In,Ga)Se ₂ (CIGSe) 太阳能电池稳定性的影响。对于 CIGSe/In ₂ O ₃ :SnO ₂(ITO) 界面，通过在 ITO 沉积期间在 CIGSe 表面引入陷阱辅助复合来保持欧姆接触。通过时间分辨光致发光 (TRPL) 研究退火后的 CIGSe/ITO 界面。发现由于溅射损伤，在 ITO 沉积后，所有研究的样品的 TRPL 寿命急剧下降，而在 160°C 热处理后，TRPL 寿命趋于增加。这种增加归因于退火过程中溅射损伤的部分恢复；与溅射损伤较严重的样品相比，溅射损伤较轻的样品的增加更大。与在界面处具有非欧姆接触的柔性双面太阳能电池相比，在 CIGSe/ITO 界面处具有类欧姆接触的柔性双面太阳能电池显示出优异的性能和长期稳定性，这可能与 ITO 沉积过程中亚稳定性的改变和/或部分恢复溅射损伤。具有类欧姆背接触的最佳柔性双面 CIGSe 太阳能电池在超过 70 天的时间内表现出稳定的性能，正面和背面照明的效率分别为 11.1% 和 3.0%。