講演情報
[21p-B203-4]Improved bottom cell current in perovskite/silicon tandem solar cells by double-sided nanopyramid Si texture
〇(D)Yuqing Li1, Hitoshi Sai2, Calum McDonald2, Zhihao Xu2, Yasuyoshi Kurokawa1, Noritaka Usami1, Takuya Matsui2 (1.Nagoya Univ., 2.AIST)
キーワード：
silicon/perovskite tandem solar cell、double-sided nanotextured silicon、interface morphology
Stacking Si with a wide-gap perovskite enables to overcome the single-junction Shockley-Queisser limit in Si photovoltaics,[1-3] offering the merits of increasing efficiency without adding substantial cost. Most of the currently reported perovskite/Si tandems are based on Si solar cell with a front-planar rear-textured structure to make them compatible with the commonly-used solution-based perovskite cell fabrication processes, which limits further efficiency improvement of tandem cells because of the high optical reflection losses.[3] In this study, we used an original Ag-assisted etching method[4] to fabricate nanometer-sized Si pyramid (nanopyramid) textures ranging from ~400 to ~1100 nm and applied them in the perovskite/Si tandem solar cells. These wafers were subjected to our standard Si heterojunction cell process and the both-side textured Si bottom cells were obtained. Here we applied a front junction cell configuration with a nanocrystalline Si recombination junction layer.[5]
Compared to front-planar Si, Si substrates with both-side nanopyramid textures exhibit markedly higher light absorption.[4] Meanwhile, from the SEM cross sectional view (Fig. 1(a)), the nanoscale texture size facilitates the subsequent uniform deposition of perovskite layer when the texture size is smaller than ~500 nm. We also confirmed that, compared to the reference cell, the spectral response in the bottom cell was enhanced by introducing the textures on both sides even though the size of pyramids rather small, which can be confirmed in Fig. 1(c). These results indicate that Si bottom cells with nano-sized pyramids are compatible with the solution-based process for perovskite top cells, and have the possibility to enhance the conversion efficiency with a simple process.
Compared to front-planar Si, Si substrates with both-side nanopyramid textures exhibit markedly higher light absorption.[4] Meanwhile, from the SEM cross sectional view (Fig. 1(a)), the nanoscale texture size facilitates the subsequent uniform deposition of perovskite layer when the texture size is smaller than ~500 nm. We also confirmed that, compared to the reference cell, the spectral response in the bottom cell was enhanced by introducing the textures on both sides even though the size of pyramids rather small, which can be confirmed in Fig. 1(c). These results indicate that Si bottom cells with nano-sized pyramids are compatible with the solution-based process for perovskite top cells, and have the possibility to enhance the conversion efficiency with a simple process.