论文标题
亚稳态缺陷降低了太阳能电池的填充因子
Metastable defects decrease the fill factor of solar cells
论文作者
论文摘要
CU（IN，GA）基于SE2的太阳能电池超过23％的功率转化效率。然而，这些太阳能电池的填充因子（最佳值约80％）相对较低（SI达到84.9％），主要是由于二极管因子大于一个。最近，我们提出了亚稳态缺陷，这是Cu（In，GA）SE2合金的一般特征，是增加二极管因子的起源。我们通过依赖激发的光致发光来测量裸吸收层的二极管因子。对于高质量，因此高发光的多晶吸收器，我们评估了四个数量级的二极管因子激发依赖性。使用模拟和亚稳态缺陷的模型，我们可以很好地描述有关N-和P型外延膜以及多晶体吸收器的实验发现，从而为该模型提供了其他证据。我们发现，通过光致发光测量的二极管因子对在成品太阳能电池上进行电测量的二极管因子施加了下限。有趣的是，最低的二极管因子（光学和电气），因此由Ag合金（即AN（Ag，Cu）（IN，GA）SE2吸收剂获得的最高填充系数为81.0％。这一发现暗示了增加填充因子的途径，从而提高了Cu（IN，GA）基于SE2的太阳能电池的效率。
Cu(In,Ga)Se2 based solar cells exceed power conversion efficiencies of 23 %. Yet, the fill factor of these solar cells, with best values around 80 %, is relatively low (Si reaches 84.9%) mostly due to diode factors greater than one. Recently, we proposed metastable defects, a general feature of the Cu(In,Ga)Se2 alloy, to be the origin of the increased diode factor. We measure the diode factor of the bare absorber layers by excitation-dependent photoluminescence. For high quality and thus high luminescent polycrystalline absorbers, we evaluate the diode factor excitation dependence over four orders of magnitude. Using simulations and the model of metastable defects, we can well describe the experimental findings on n- and p-type epitaxial films as well as the polycrystalline absorbers, providing additional evidence for this model. We find that the diode factors measured optically by photoluminescence impose a lower limit for the diode factor measured electrically on a finished solar cell. Interestingly, the lowest diode factor (optical and electrical) and consequently highest fill factor of 81.0 % is obtained by Ag alloying, i.e. an (Ag,Cu)(In,Ga)Se2 absorber. This finding hints to a pathway to increase fill factors and thus efficiencies for Cu(In,Ga)Se2-based solar cells.
