The efficiencies of all-perovskite tandem devices are improving quickly. However, their complex interconnection layer (ICL) structures—with typically four or more layers deposited by different processes—limit their prospects for applications. Here, we report an ICL in all-perovskite tandem cells consisting merely of a fullerene layer and a SnO_2–x (0 < x < 1) layer. The C₆₀ layer is unintentionally n-doped by iodine ions from the perovskite and thus acts as an effective electron collecting layer. The SnO_2–x layer, formed by the incomplete oxidization of tin (x = 1.76), has ambipolar carrier transport property enabled by the presence of a large density of Sn²⁺. The C₆₀/SnO_1.76 ICL forms Ohmic contacts with both wide and narrow bandgap perovskite subcells with low contact resistivity. The ICL boosts the efficiencies of small-area tandem cells (5.9 mm²) and large-area tandem cells (1.15 cm²) to 24.4% and 22.2%, respectively. The tandem cells remain 94% of its initial efficiency after continues 1-sun illumination for 1,000 h.

全钙钛矿串联设备的效率正在迅速提高。但是，其复杂的互连层（ICL）结构（通常具有四层或更多层通过不同的工艺沉积）限制了其应用前景。在这里，我们报道了仅由富勒烯层和SnO _{2– x}（0 <  x  <1）层组成的全钙钛矿串联电池中的ICL 。C ₆₀层无意间被钙钛矿中的碘离子n掺杂，因此作为有效的电子收集层。由于锡的不完全氧化（x  = 1.76）而形成的SnO _{2– x}层由于存在大密度的Sn ^2+而具有双极性载流子传输性质。C ₆₀ / SnO _1.76 ICL与具有低接触电阻率的宽禁带和窄禁带钙钛矿亚电池形成欧姆接触。ICL将小面积串联电池（5.9 mm ²）和大面积串联电池（1.15 cm ²）的效率分别提高到24.4％和22.2％。连续照射1小时后，串联电池仍保持其初始效率的94％。