We studied the impacts of front contact layers composed of transparent conducting oxide (TCO) and transparent oxide semiconductor (TOS) layers on the performance of Cu(In,Ga)Se₂ (CIGS) solar cells with glass/Mo/CIGS/CdS/TOS/TCO in relaxed and metastable states. After annealing under illumination, the CIGS solar cells with KF and NaF postdeposition treatments exhibited metastable increases in open‐circuit voltage, fill factor, and the resulting conversion efficiency with a metastable decrease in short‐circuit current density. These are partly attributed to an increase in metastable acceptor density in the CIGS layers, being stable for a day even at room temperature, with a reduced space charge width. We found that the net acceptor density evaluated by capacitance‐voltage measurements largely varied depending on the TOS/TCO layers, whereas the open‐circuit voltage was identical. On the other hand, no significant differences in both the net acceptor density and open‐circuit voltage were observed regardless of the TOS/TCO layers in the relaxed state produced by annealing in the dark. The results suggest that the CdS/CIGS heterojunction can no longer be treated as an n⁺/p junction in the metastable state and that the evaluated acceptor density was apparent values with large difference originating from different potential distribution in the CdS layer, which is related to the TOS/CdS and TCO/CdS junctions. In addition, the TOS/TCO layers largely affected the short‐circuit current density owing to their optical constants and film thicknesses. The presented results highlight the importance of the design of CdS/TOS/TCO layers in solar cells operated in metastable states.

中文翻译：

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在松弛和亚稳态下，前接触层对Cu（In，Ga）Se2太阳能电池性能的影响

我们研究了由透明导电氧化物（TCO）和透明氧化物半导体（TOS）层组成的前接触层对Cu（In，Ga）Se _{2性能的影响}（CIGS）具有松弛状态和亚稳态状态的玻璃/ Mo / CIGS / CdS / TOS / TCO的太阳能电池。在照明下退火后，经过KF和NaF沉积后处理的CIGS太阳能电池的开路电压，填充系数显示出亚稳态的增加，并且转换效率随着短路电流密度的亚稳态而降低。这些部分归因于CIGS层中亚稳态受体密度的增加，即使在室温下一天也稳定，空间电荷宽度减小。我们发现，通过电容电压测量评估的净受体密度在很大程度上取决于TOS / TCO层，而开路电压是相同的。另一方面，无论在黑暗中退火产生的松弛状态下的TOS / TCO层如何，都没有观察到净受体密度和开路电压的显着差异。结果表明，CdS / CIGS异质结不再被视为n ⁺ / p结处于亚稳态，并且所评估的受体密度是表观值，其差异很大，其源于CdS层中不同的电位分布，这与TOS / CdS和TCO / CdS结有关。此外，TOS / TCO层由于它们的光学常数和膜厚，在很大程度上影响了短路电流密度。提出的结果突出了在亚稳态工作的太阳能电池中CdS / TOS / TCO层设计的重要性。