Department of Materials Science and Engineering and ‡Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
ACS Appl Mater Interfaces. 2017 Dec 6;9(48):41863-41870. doi: 10.1021/acsami.7b12886. Epub 2017 Nov 22.
In this paper, the integration of metal oxides as carrier-selective contacts for ultrathin crystalline silicon (c-Si) solar cells is demonstrated which results in an ∼13% relative improvement in efficiency. The improvement in efficiency originates from the suppression of the contact recombination current due to the band offset asymmetry of these oxides with Si. First, an ultrathin c-Si solar cell having a total thickness of 2 μm is shown to have >10% efficiency without any light-trapping scheme. This is achieved by the integration of nickel oxide (NiO) as a hole-selective contact interlayer material, which has a low valence band offset and high conduction band offset with Si. Second, we show a champion cell efficiency of 10.8% with the additional integration of titanium oxide (TiO), a well-known material for an electron-selective contact interlayer. Key parameters including V and J also show different degrees of enhancement if single (NiO only) or double (both NiO and TiO) carrier-selective contacts are integrated. The fabrication process for TiO and NiO layer integration is scalable and shows good compatibility with the device.
在本文中，我们展示了将金属氧化物集成作为载流子选择性接触材料用于超薄晶体硅 (c-Si) 太阳能电池，这使得效率提高了约 13%。效率的提高源于这些氧化物与 Si 的能带偏移不对称导致接触复合电流的抑制。首先，我们展示了一种总厚度为 2μm 的超薄 c-Si 太阳能电池，在没有任何光捕获方案的情况下具有超过 10%的效率。这是通过将氧化镍 (NiO) 集成作为空穴选择性接触层材料来实现的，NiO 具有较低的价带偏移和较高的导带偏移。其次，我们展示了一个具有 10.8%的冠军单元效率，通过额外集成氧化钛 (TiO)，TiO 是一种用于电子选择性接触层的知名材料。如果集成单个（仅 NiO）或双（NiO 和 TiO 都集成）载流子选择性接触，则包括 V 和 J 在内的关键参数也会显示出不同程度的增强。TiO 和 NiO 层集成的制造工艺具有可扩展性，并且与器件具有良好的兼容性。
