Tuning band gaps with three halides Tandem solar cells can boost solar cell efficiency by using two active layers to absorb the solar spectrum more completely, provided that the two cells are current-matched. Inorganic-organic perovskites tuned to the appropriate wide band gap (∼1.7 electron volts) as top cells that contained iodine and bromine or bromine and chlorine have short carrier diffusion lengths and undergo photo-induced phase segregation. Xu et al. now report a method for incorporating chloride that allows for fabrication of stable triple-halide perovskites with a band gap of 1.67 electron volts. Two-terminal tandem silicon solar cells made with this material had a power conversion efficiency of 27%. Science, this issue p. 1097 Metal halide perovskites containing chlorine, bromine, and iodine had higher band gaps that led to more efficient silicon solar cells. Wide–band gap metal halide perovskites are promising semiconductors to pair with silicon in tandem solar cells to pursue the goal of achieving power conversion efficiency (PCE) greater than 30% at low cost. However, wide–band gap perovskite solar cells have been fundamentally limited by photoinduced phase segregation and low open-circuit voltage. We report efficient 1.67–electron volt wide–band gap perovskite top cells using triple-halide alloys (chlorine, bromine, iodine) to tailor the band gap and stabilize the semiconductor under illumination. We show a factor of 2 increase in photocarrier lifetime and charge-carrier mobility that resulted from enhancing the solubility of chlorine by replacing some of the iodine with bromine to shrink the lattice parameter. We observed a suppression of light-induced phase segregation in films even at 100-sun illumination intensity and less than 4% degradation in semitransparent top cells after 1000 hours of maximum power point (MPP) operation at 60°C. By integrating these top cells with silicon bottom cells, we achieved a PCE of 27% in two-terminal monolithic tandems with an area of 1 square centimeter.

中文翻译：

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三卤化物宽带隙钙钛矿抑制相分离，实现高效串联

用三个卤化物调节带隙串联太阳能电池可以通过使用两个有源层更完全地吸收太阳光谱来提高太阳能电池效率，前提是这两个电池电流匹配。无机-有机钙钛矿调整到适当的宽带隙（~1.7 电子伏特），因为顶部电池含有碘和溴或溴和氯，具有较短的载流子扩散长度并经历光致相分离。徐等人。现在报告一种掺入氯化物的方法，该方法允许制造带隙为 1.67 电子伏特的稳定三卤化物钙钛矿。用这种材料制成的两端串联硅太阳能电池的功率转换效率为 27%。科学，这个问题 p。1097 含氯、溴、碘具有更高的带隙，从而导致更高效的硅太阳能电池。宽带隙金属卤化物钙钛矿是一种很有前途的半导体，可以与串联太阳能电池中的硅配对，以实现以低成本实现大于 30% 的功率转换效率 (PCE) 的目标。然而，宽带隙钙钛矿太阳能电池从根本上受到光致相分离和低开路电压的限制。我们报告了使用三卤化物合金（氯、溴、碘）来调整带隙并在照明下稳定半导体的高效 1.67 电子伏特宽带隙钙钛矿顶部电池。我们展示了光载流子寿命和电荷载流子迁移率增加了 2 倍，这是由于通过用溴代替一些碘来缩小晶格参数来提高氯的溶解度。我们观察到，即使在 100 太阳光的光照强度下，薄膜中的光诱导相分离也受到抑制，并且在 60°C 下最大功率点 (MPP) 运行 1000 小时后，半透明顶部电池的退化小于 4%。通过将这些顶部电池与硅底部电池集成，我们在面积为 1 平方厘米的两端单片串联中实现了 27% 的 PCE。